The GTS-V is basically an underclocked GF2 GTS... running at 175/143 compared to the 200/166 of the regular GF2 GTS.
2D visual quality is comparable to most other VisionTek cards, which is to say it's pretty good... still lacking compared to Matrox/3dfx/ATi but it's better then most nVidia boards offer.
3D visual quality is comparable to most any other nVidia GF2 board, which is quite good overall.
Overclockability tends to vary dramatically between GTS-V's, and VisionTek has changed the DRAM beng utilized on their GTS-V's a few times.
I've heard reports ranging from slightly above GF2 Pro speeds of 200/200, to overclocks below that of the GF2 GTS default clockspeed.
Most of them seem to hit around 200-210/166-175 though.