I'm at the tail end of my vacation time from work, so I could not resist going out and buying Diablo 3 for the Xbox 360 yesterday. It is super rare that I ever buy a game when it first comes out, but I was impressed enough with what I'd played of the PC version to give it a shot. If nothing else, the boost in frame rate of the Xbox 360 version compared to my low-spec PC would be a welcome thing.
I installed the game to my hard drive and it took 6.7GB of space. I went to go launch the game and it said something to the effect of me needing to update my Xbox 360 dashboard and security (not their words) before the game would launch. I'm not on Xbox Live at all, so I had to go to the Xbox website to download the latest dashboard. I did this on my PC and put it onto a USB stick and was able to update my dashboard without any difficulty. Then the game did launch after that.
I played Diablo 3 for at least four hours yesterday and really had a lot of fun with it. I created a witch doctor and have him up to level 11 already. The frame rate is indeed worlds better than my PC, even with lots of stuff happening on the screen, but it is true that aiming at enemies is not as precise as having a mouse. Even so, I've adapted quite well. For melee characters it would probably be awesome. Also I should point out that the camera is zoomed in closer the action than the PC version so sometimes enemies do come up on you quickly. Additionally, one minor annoyance I've had is that when I am close to the entrance of a dungeon and I go to attack someone with the A button on the controller (which is also the main action button), sometimes I will accidentally exit the dungeon rather than attack the enemy. Not a big deal but something to keep in mind. Monster Power does exist in the console version, but each level has a different name than the PC version. You have easy, normal, and hard difficulties and then Master Levels 1 through 5.
The game manual is almost non-existant. All I got for documentation was a card with a redemption code key for the Infernal Helm on Xbox Live, and a fold-open "manual" which gives a health warning about photosensitive seizures, the software license agreement, and the controller scheme. That's the extent of the documentation. There's not even a link that I could see about downloading the manual. I guess they are trying to push as many people as possible into getting the strategy guide, but of course the Internet is a good resource too.
Overall, I'm having a lot of fun with the console version of this game and would recommend it. Bear in mind however that I never played much beyond normal difficulty in the PC version due to the terrible frame rate of my GeForce 8200 graphics chip.
Sorry for the long post!