When I bought Rock band for the first time all my friends moaned about the guitar controller, going 'its too plasticy' and 'the GH controller is better, it feels better'. This guitar is awesome and better than the guitar hero model, and here's why -
when i had both at uni, me and my friends spent time playing with both controllers and all agreed the rock band one was awesome and the GH one was lame. it is easier to play difficult songs on this one than the GH guitar; the fret buttons are next to each other making it easier to slide your hand over them. the GH controllers look garish, the RB ones nice and simple.
The most disturbing thing with the GH controller is that 2 years after buying the RB controller i bought guitar hero 5 with a GH controller, and 6 months later the GH is completely broken - the blue button doesnt work, neither does the whammy bar and the strummer will only strum upwards. this was after 6 months of use compared to the 2 years of use with the RB controller, which, frankly, we used more anyway. the only field the GH is superior in is the strummer.
If your trying to chose between the two, go for this one. it doesnt work on guitar heros 1 2 and 3, however, but does on world tour, greatest hits, aerosmith, metallica, van halen and 5. and obviously all the rock band games.