I've had 2 Inno3D cards (GF2 & GF3), no problems with either, other than the fan crapping out on the GF3. It was a Thermaltake Blue Orb, easily replaced, and hard to fault Inno3D for it's failure. The GF3 is still in use in my other system after 2.5 years.
It's possible that in some cases their cards won't overclock as high as another brand, but I've seen some reviews that indicate the opposite. Nothing's guranteed when you're talking about overclocking.