all games are not created equal

DJ Hero is a clear win on this one.  I never had fun playing GH by myself; it's just meant to be played with other people.  DJ Hero isn't like that though.  It's actually almost the exact opposite, where group play isn't really worth it. 

DJ Hero is a ton of fun to play and it's one of the only music simulations that actually made me feel like I was controlling the music and not just playing along.  GH is still cool, but just doesn't connect to the music nearly as much as DJ Hero does.

DJ Hero is also pretty challenging in a very new way, which is extremely refreshing given how long guitar controllers have been around. 

Biggest point against DJ Hero though is that it's pretty expensive.  Despite the price point, I still am glad that I bought it and will continue to enjoy it down the road.

After World Tour, Metallica, and Smash Hits all coming out just seemingly one after another, I couldn't think of a reason why we needed Guitar Hero 5.  Truth is, I still don't think we did, but I appreciate the little additions.

If I had to find one big difference with GH5, it'd be the ability to drop in and out of songs at will.  Now this may not seem like a huge difference, and it isn't if you just play by yourself, but this makes the game much more accessible for parties and such.
I guess this time, it feels like the designers really put forth the effort to make the game as easy to pick up as possible.  Any combination of instruments you have will work, even if they're from Rock Band or previous generations of Guitar Hero. 

I don't have any major gripes, except that I just do not care for the song list all that much.  Most the songs I don't recognize, yet alone the artists.  Maybe it's cause I just like classic rock and such more, but the song lists really seem like the designers are just choosing their own favorites, instead of going for a big mass appeal.
I mean, I like variety and all, and it'd be stupid to have a music game with just one kind of music, but I at least enjoy recognizing the artists.  Whatever.

Anyway, the career progression is much much quicker this time.  You'll be blazing through venues like no tomorrow.  Each song has a challenge associated with it too.  The challenges are instrument specific, or they apply to a band of two or more people.  I only played through on guitar, and guitar challenges were something like "Nail as many hopo's as you can", "Wammy sustains as much as you can", "Get your streak up as high as you can", etc etc.  No biggie, but it's nice to get a little extra bonus.  The wammy sustains was annoying though, cause it had me constantly wammying every note I could, and really just made playing the song uncomfortable.

Most everything else is generally unchanged.  You have a few cosmetic changes here and there, new venus, characters, etc.  But overall you get the same, plus more.

This is purely based on controllers.

The guitar controller on Rock Band is MUCH more comfortable and practical than the GH:WT or GH5 controller.  The fret buttons take up the FULL FRET, as opposed to the childish smaller buttons on the GH controller.
The strum bar is a matter of preference.  RB's is completely silent, but it's also a little tougher to be precise on fast patterns.  GH's is still clicky, but it's fairly quiet and you barely hear it if you crank your sound up as much as I do, and it's perfect for fast patterns.

I much much MUCH prefer the solo buttons over GH's slider.  The slider just isn't implemented well.  Transitioning from the normal buttons to the slider is just terrible and pointless.  You might as well just stay on the buttons the entire time.  However, with RB's solo buttons, I can transfer there and back with ease.  They're smaller, so there's less finger movement, and I can feel where the buttons are when I play.

As for the drums, again, it's a matter of preference.  The kick pedal is far superior in RB, IMO.  I'll give GH credit for having cymbals a part of the base installation, and the pads are quieter, but otherwise I once again prefer the RB drums.
I have the three cymbal expansion for RB, and I love 'em.  It makes it really satisfying to roll the snare, toms, and then finish with a cymbal crash.  Plus in free play, you pretty much have an entire drum kit, so you should be able to play any song you want :)

Vocals... eh whats there to say.  Who plays vocals?