This is the most impressive game launch in years, and is likely to prove to be the second MMO to reach the stature of World of Warcraft.
You should find yourself familiar with many of the game mechanics - generate a character, go questing, level up, join battlegrounds to play some PvP. No player should have any difficulty in getting into the game and having a good time. That said there are nuances that really polish up the playing experience and make it better than anything we've seen before - for example in every zone there are 'points of interest' and 'viewpoints' marked on the map, and you're rewarded for visiting them - in practice this means that you're rewarded for taking a little time out of the hack & slash to go exploring/puzzling to get up to the top of the tower and appreciating the beautiful world that the developers have made for us. You don't have to talk to a quest giver, or hand the quest in (though you can for a little colour if you like) - just stroll into the quest area and it will come up and you can get involved. The world is very slick, very beautiful, and absolutely vast.
The mechanics of gameplay are similarly refined. For combat itself you have up to 10 active abilities that work on cooldowns (there's no mana/rage requirements or similar). The abilities are determined by which type of weapons you have equipped, and most classes can easily switch between two weapon sets. For example as a warrior you can stroll around with a bow equipped which does pretty heavy damage if you get the drop on someone, then when they get to you you could switch to a sword and shield, replacing five of your abilities with slash/block moves to keep the guy busy while you finish him off. What this means is that there's a good deal of versatility available to every class through using the different weapons you can equip. Every class can greatly up their damage/toughness/support if they so desire at the expense of the other strengths. For example the elementalist (a very versatile class) can go fire (pure dps) air (good dps + some crowd control) water (weak dps + support healing) or Earth (moderate dps + movement debuffs) AND has a selection of underlying abilities for those aspects depending what weapons they are using. From the first you get the impression of minutes to learn, but a lifetime to master. The remaining five abilities are unlocked with level. Every class can heal itself.
So is it any fun? GW2 scores big here. There are simply no grinding time sinks. You want to play PvP? You're automatically shifted to max level and given max gear when you go to a battle ground, and can just play. PvP comes down to skill, you'll never be bested by gear, and you can start playing at top level pretty much straight away if you so desire. You want to travel to the other side of the world? You can port to any waypoint from anywhere else (out of combat) for a trivial amount of cash. You want to play with your mate who's ten level lower? No problem, you get automatically downleveled when you go to an earlier zone, so your power will be shifted down to what's appropriate for that zone and away you go, rewarding you for playing all over their enormous world. Will I have to spend hours killing wombats to level up? Nope, the quests tend to be fairly interesting (but certainly not as good as in Star Wars Old Republic, who to my mind set a new standard), and there's no shortage, so if you don't fancy getting polymorphed into a pig to search for truffles, just move on. In combat movement is very important, both positioning (you'd be amazed at the impact a well placed tree can make) and dodging. The dodges work off energy, and are crucial to success - this will really help to keep the combat fresh and stop it being just a click/gear check.
The world is lovely, and hats off to the viewpoint idea which really stops you to appreciate it. The cut scenes are nicely done, but you only get those for your personal quests. The character graphics are of a high standard, allowing you to personalise in character generation, and customise you gear a bit too. I rate the character representation as pretty good, although as my characters are tiny it's hard to be sure :)
Crafting is something that you can address when you're in the main cities. At any time, from any place you can click a button to move all crafting materials from your backpack to your bank, then from the cities you can use the materials at the crafting points to make what you want. There is allot of Xp available from gathering and crafting rewarding the early endeavour, the gear is pretty level equivalent, though having `best in slot' gear to hand as you level up is useful.
For the end game the crafted exotic gear is basically the best available, but is freely traded on the auction house, so if you're not bothered you'll lose very little by just flogging the mats you accumulate in the AH and buying the gear you want.
Now you'll need the skills levelled if you want build the legendary items, but these are just visually more impressive, they give no gameplay advantage, and there is a massive investment required to get the extra `sparkle'. You can have two crafting skills active, but if you ditch one you don't lose any of your advances, it's just inactive.
General chat is about what you'd expect, and probably always will be. Aside from that on the positive you can join as many guilds as you like, facilitating specialisation. On the downside there is no functionality around getting a party together to run an instance - we're back to the old school standing in a city or outside the instance spamming "LF2M AC Explorer" messages in general chat. There were serious issues with getting your mates into the same `shard' of a location (shards are like separate instances of an area map to handle the overflow if too many players enter), but these have been fixed - there are now no issues with teaming up with your mates.
The game makes heavy use of your CPU (rather than graphics card) to run - so unless your PC is up to date, you'd be well advised to closely inspect the system requirements. I bought a bleeding edge PC 5 years ago, and it just can't handle the traffic of twenty guys shooting at each over in the World vs World battleground. There's a handful of bugs in the game (remarkably few for the launch of such an ambitious game), the log in server can't handle spike traffic, and the error messages you get don't give you any indication of what the problem is. The biggest irritation is the lack of support for getting the four extra players you need to run an instance - not only are you reduced to spamming general chat in Lions Arch, but after a couple of posts the game stops you from posting any more "due to excessive messaging" - really annoying when you're desperately trying to find the last man. That's it. Seriously, this is a VAST game, with no subscription charges, that's only been out for a few days and it's as polished as a diamond. Very very impressive, and gets full marks from me. It's also worth mentioning that when the servers go down (rare) the lines of communication are very good, which reduces the annoyance factor considerably. There are regular patches & updates, but these only last for a couple of minutes, so unless you're in the middle of an instance they don't really affect gameplay.
There's very little to fault in this game, and as an MMO it's simply better that WoW, and that is no mean feat on launch day. Time will tell how the longevity stacks up, so far the instances keep you on your toes and the pvp is of very mixed ability. Because it's not particularly difficult to get max gear, there isn't a huge grind to see the top content - personally I like this, not only do I play the game for the sake of just playing it & having fun, but I can also do other things without losing out. If WoW was crack, GW2 is more like a nice pint - yourself & your mates will find yourself knocking back a couple with a smile on your face, without the wild eyed compulsion, sleep deprivation & broken relationships that Warcraft left in it's wake. It's just fun, it's not a second job.
I have absolutely no qualms in giving GW2 a hearty recommendation. It's a superb game, the most impressive MMO in many years, all yours for a one off payment, and I'm certain that it's going to take off in a big way.