Lots of differing voices of opinion here! It's like Assassins Creed all over again! Now I wasn't keen on Assassins Creed... I bought it and I play it, but I couldn't get past the concept of a Assassin as openly clumsy and careless as the one portrayed by the game. No such trouble here though! You're a Viking! Vikings hack people to pieces and do little else!
Levels are map based and revolve around ticking all the boxes to unlock the main battle. These boxes are generally Build an army (by rescuing captured Vikings) and Summon a dragon (by obtaining a magical stone and charging it) Rescuing Vikings is a straight forward affair. Go to the markers on the map and slice and dice til everythings dead. It's not always that straight forward though... lots of enemy camps are heavily populated and require a stealthy 'pick them off' approach to release the captives who will then run around decapitating anyone left with you to take control of the camp.
Dragon summoning is similar. First you have to obtain the magical stone, again by hacking/slicing a pre marked area on the map... once you have the stone you need to charge it.... and the charging of the stone is probably the most challenging aspect of the game. Charging requires you to infiltrate the enemy camp - the big one - where the final battle will take place! Now, if you make too much noise then there is no way to fight off the ensuing mass of demon spawn that come after you. So a stealthy apporch is the only way to go. This is also the most frustrating part of the game while you try and figure out the correct approach path to lead you to the magical charging circle. But once done you really do feel the sense of achievement because they really are challenging moments.
Combat is pretty simple. Although not the hack and slash affair that a lot of people seem to think! You can buy training to learn new combos at set point on the map which unlock more powerful attacks. These new attacks are crucial! Even at a lower levels of the game its pretty hard to beat the shield carrying baddies without learning your shield busting combo attack! So, if you don't want to die too frequently then using the correct attack against the correct enemy is crucial.
Combat is also fancied up by the use of empowering your weapons with elemental powers - fire, ice and lightneing - which basically makes them more powerful and the going a little easier. However this isn't something you can use willy nilly as orbs left behind by dead enemies are required to be collected to charge the attacks.
There are also a few side quest require to get some groups of vikings to aid you in battle but these are also in the 'go to marked location and hack enemys for token item' approach - but it does seem to add some sense of variety to the proceedings.
Once unlocked the final battles are also a challenge. There is a little strategy in when and where to unleash your dragon attacks, other than that its a case of stopping the summoners from creating more demons that will take out your poor overworked vikings. It's all very intense and bloody!
So to conclude... I've found it great fun to play! It's repetative... but so was Assassins Creed... its good looking ... its bloody ...and it's challenging... I've found no problems with anything (people complaining about the darkness/daylight thing is a bit unfounded I feel) ... it is what it is! It's not pretending to be a deep and complex game... although its actually slightly more complex than I was expecting! If I was marking out of ten - I'd give it an 8 ... it's obviously not to everyones taste, but for everyone who hates it another will love it.... it's very well worth a try :)