Plenty of negative things said about them. I own one of their 1600 watt amps so I'll throw out my opinion:
**IT ALL DEPENDS ON PERSONAL TASTE** Perfect example would be every single one of those morons in my town that love to push the bass so hard that, not only can you not hear the highs(guitar solos, vocals, cymbals, ect.), and you have trouble breathing inside the car! If that is your kind of thing then stay away from Cuspid. Get something expensive and that is built to push that kind of stuff.
As for what I need it for, it works great! I wouldn't suggest pushing ANYTHING higher than 10"s. Their amp wiring kits work just fine.
Their speakers are terrible. Spend your money on something better, Like BLITZ.