I've spent the last few weeks doing some research on which to buy, and finally caved and bought a PSP GO. I ended up returning it and buying the PSP 3000, and here's why:
1. Physical comfort.
I'll admit it, I'm a sucker for things that are new and look cool (sometimes at the cost of utility.) Plus, things that slide are undoubtedly awesome. Sony knew that when they made the GO. The problem is the "cool" and "new" factors are outweighed by the smaller screen and compressed controls. Also, I thought it would be better having the controls on the bottom wh en gaming, and have a less distracting view when watching movies since the buttons would be hidden, but I was wrong. The buttons on the side are far more comfortable, convenient, and surprisingly natural. The bigger screen actually does make a difference, and the L and R buttons just feel more natural this way.
One thing to note about the screens (both have the same resolution):
They're good, but not great. The problem is we're spoiled now. If you have a smartphone (which if you don't, I feel like I don't even know you,) you'll be disappointed when you see some things on the screen that are just so clearly pixelated. I'm going to post a video review in a bit and you'll see what I'm talking about.
2. Digital games vs. UMD (the names of the physical discs that the 3000 uses.)
For those who don't know, the PSP GO uses digital games exclusively. There are no physical discs. You download games from the Playstation Network store. It's convenient since you don't have to carry discs around, and you have immediate access to a huge selection.
The 3000 uses physical discs (UMD) as well as downloads. Now, carrying discs around is definitely a hassle (even though they're only about 2 inches by 2 inches), but the benefit is that you can buy used discs for very cheap, an option not available with the digital only GO.
At GameStop, you can buy used PSP UMDs for cheap, and they have a great return policy. For any reason, you can return any used game within 7 days for a full refund, to any GameStop in the country. If you don't have your receipt, you have to return it to the location where you bought it.
This is often overlooked but I think very important. The retail price for the GO is $250, which is pretty crazy given that you can often find a PS3 for $250, or at worst, $300. Given that you can get a full system for 20% more, it's hard to justify spending that much for considerably less functionality.
Now on Amazon you can get the GO go for $200, plus tax and such leads to about $215. On NewEgg, you can get the PSP 3000 with Madden 11, free shipping and no tax for $170. So you'll end up paying at least $45 more, but for what?
You are really spending $45 more for no reason. And with this extra $45, comes the responsibility to spend even more on games that you buy directly from the PlayStation network as opposed to used UMDs.
4. Memory Stick
If you do decide to get a GO, it uses something called the M2. If you buy it from Amazon, you get a 4GB for $15 and it comes with an adapter for the Memory Stick Duo:
If you buy a 3000, it uses the Memory Stick Duo, which if you buy by itself, a 4GB will run you ~$19:
I know it's only a matter for $4, but I thought that was interesting (I need to get out more) and worth mentioning.
5. Fun level
They're both freaking fun. Sony knows what they're doing, the games are great, the devices are both portable and easy to take around, and keep you entertained for hours. Either way, you'll love what you bought.
6. WRAP UP
I ended up with a 3000 and I'm happy with it. I couldn't justify spending nearly as much money as I would on a full system without getting much in return. And the ability to buy used games for considerably less was also hugely attractive. Finally, the better placement of the controls really won me over.