I just built a HTPC in a Silverstone GD05B and I thought it was an absolute pleasure. The case itself feels so solid, but not heavy, and every part that moved or slid did it smoothly.
However if you're going for a performance rig, it's not really ideal because the optical drive sits just above the CPU, and thus the heatsink, so you'd need something pretty low profile. I went with a Scythe Big Shuriken.
Honestly, relative to the experience, I liked the Silverstone better than my Lian Li PC-9F midtower; admittedly they're completely different case styles and builds, but I think the Silverstone felt better. The Lian Li panels just felt like I had to force them all the time and seemed more fragile.
Edit: Crap, I said SG05, I meant GD05B.