Not as good as Part 3, but still Good
As for GH: World Tour to put it short it's more of the same, but this time in band form. You get a list of songs which you can choose to play the guitar, sing, be a drummer, or perform bass. I personally just sing and play guitar, and while I am pretty sure I suck at singing it's still always fun to mess around with a good song and just lose your mind.
Graphics-- This is so standard it's not even funny. You get different character Models who perform the same motion captured moves depending on what song you are playing. While the characters artistic designs haven't changed they are more stream lined and updated. You can clearly make out words or notes that need to be played without the back ground animations getting in the way. Of course I haven't played a full band at one time, but I'm fairly sure it's akin to Rock Band in some respects. Don't expect a lot by the way of graphics let's leave it at that.
Music-- Heck this is what the games all about. It has great sounds and uses original recordings. At some point in songs if you are doing well the crowd will even join in which is killer. On the other hand the song list is weaker when compared to the likes of GH 3 or Rock Band. I love "Eye of the Tiger" and "Living on a Wing and Prayer" but other songs (which there are a lot of them) I could care less about and when doing the career mode needlessly play to get to the next set. It's your standard fare of near perfect sounding, but not always a good song thing going on.
Game play-- If you have played the GH or RB series then you will know that you need to match on screen prompts of different colors while strumming your guitar to make a song work. While singing is a simple as picking up the mic and blasting vocals into it, Beware as pitch and inflection need to be somewhat spot on. I don't play the drums so I won't comment on it. I think that if you have at least a little rhythm in you, you can get this game to operate on at least "very easy" mode. I can play on medium which is asking a lot of my fingers, but I love the challenge. Something about these games gives you a sense of accomplishment when you see you were able to strum along to the songs end. It's good clean fun and can be enjoyed again and again. Now that there is a full band option things are more fun should you and some buddies want to party one night. Maybe you want to jump online a shred it up, too. This would also work well whether in co-op or a band battle.
Replay value-I'd think it's fairly high especially if you love the songs on the game. I still rock out to GH 3 to see if I can do better or to just enjoy a song. So when you throw things like leader boards, co-op, online support, and making your own songs of sorts you raise the bar that much more.
For fans of these types of games I'd say get this game. It's still a blast to play and the band option opens things up nicely. I just wish they would have done the Rock band thing and made the old track available on the new game. Anyway that's my tale on GH: World tour hope this helps you out somewhat PEACE!!