There's going to be a lot of people unhappy with this game.
First off, all the hype about being able to play with whatever instrument combo you want...well throw that right out the window, unless you're happy with being limited to either two lead guitars or two bassists as the only change in option. You aren't able to have more than one drummer or singer, as far as I can tell. Also, the much advertised Rockfest feature is non-existent on the PS2 version, though there is a party mode (pretty much an endless play list of songs picked at random that you don't have to worry about failing out of the songs (I didn't see anywhere where you could join in and drop out at any point like advertised, though)), and a free play mode (make a six song set list and play without worrying about failing out).
Don't expect as many choices of GH characters (if making your own character isn't something that really appeals to you), because there aren't as many characters to choose from as there were in GH: World Tour, though there is still the same eight slots for created characters. I admit, I haven't yet completed the career mode, but from what I HAVE completed, it looks very much like Rock Band 2's career mode, right down to the addition of the star meter that let's you know when you hit the next star level, though it is visually different, anyone that's played both games with recognize it right away. They've also done away with the money reward aspect of the game, instead opting to return to the certain number of stars required to open the next venue/ set list. There are locked gigs (songs) at the start of each venue which seem to be the songs that, once completed, unlock something, usually a clothing or instrument pack, and all that seems to be required to unlock these gigs is to play one of the other songs from that venue in succession, meaning that to unlock the first one you play one song, to unlock the next one you play another song, and it doesn't seem to matter which song you choose.
That brings me to the actual song selection for the game. All I'd heard was how great this song list was, and how it was going to be the best list yet. Well, I'm going to have disagree with the hype. The list is o.k., good at best, but far from great. First off, there are too many bands that I've never even heard of, and of the band that I've heard, in many cases, the song choice isn't one that I'm familiar with nor particularly like. Then there are a couple of songs on the list that it took me a second to realize where I'd heard them before, in this case they were from MLB 09: The Show, and that got me thinking about the set list from GH: World Tour, and I realized that a few of those songs were from MLB 07: The Show (it also made me wonder if there were songs from MLB 08: The Show since I've never played that game so I don't know what music is on that game). Don't get me wrong, there are some really good songs on there, but at the same time there are a lot of really bad songs too. It is my understanding that Guitar Hero is going towards including more lesser known bands in the game, and that Band Hero is going to be a bit heavier in the direction of more mainstream bands, only time shall tell I guess.
I rated this game 7.5 because overall it is still a good game, but it doesn't live up to the expectations that all the pre-release hype set. I do realize that the next gen versions of this game do have the Rockfest mode as well as other features, and that is unfortunate that PS2 owners are getting a lesser product, but I guess that is the story of "progress". I will recommend this game if you're not looking for any dramatic changes, but I can't say that I'd recommend this game if you're going to be overly disappointed by it not living up to its hype and the missing features. Also, one plus is that all the songs are available, for the modes other than career, right away.