The music game genre is starting to wear thin, but GH5 manages to tweak the formula just enough to maintain interest.
However, GH5 is not without its faults. The setlist is incredibly varied, so you're sure to find at least one song you love on there. However, it's also varied to the point where even though there are a few songs out of the 80+ on disc that you like, the rest are just meh. If you're in to just one genre of rock, you probably won't appreciate this game for what it is, but if you're looking for an extensive library of music that goes from Jon Bon Jovi, to rap (Bring the Noise by Public Enemy), to just plain weird (Scatterbrain by Jeff Beck), you'll probably be satisfied.
GH5 shares the same Music Store as GH World Tour. That should speak for itself. The DLC seems to be focused on the abstract and obscure bands rather than the classics, ranging from European track packs (bad ones, at that), to new songs by old bands whose old songs were so much better (Eagles, anyone?). It doesn't even compare to Rock Band's library; not in quantity, and CERTAINLY not in quality.
Setlist complaints aside, Guitar Hero 5 is an incredible amount of fun. The whole lack of accessibily issue is nonexistant, and the game consistantly delivers in variety - - something music games have been missing for some time.