I have this. The guitar is very cheaply made. It's a plastic body, about 3/4th scale, so smaller frets than normal, and it's practically impossible to keep in tune. While it does technically work as a real guitar, you are not going to enjoy attempting to play with it. It will work as a guitar controller in RB/GH games, yes, but again, it's a very odd experience to try to do so. I wouldn't really recommend it. The guitar has a rubber stopper that lifts onto the neck, to keep the strings from reverberating while using it as a controller. So the strings feel very stiff and have very little give in the strum area, and are pretty much fixed in place along the neck. It's awkward all the way around. For $27, hey, maybe you get a day's worth of entertainment out of it, but don't expect anything special.
Edit: Forgot to say, the game itself reminds me of Rock Revolution. It's not very good, but it's not quite God-awful. If you can deal with the vertical, 2-D note highways, no bass play, very picky timing windows, repetitive play lists, and a quirky career mode, eh, it might be worth playing if you're a huge music game fan and want to try out a new setlist. It has a few exclusive artists (Kid Rock, Eric Clapton) but most of the good songs must be unlocked by playing half the career mode first. And there is a LOT of mediocre filler on the setlist that is unlocked right away.