I have used them in a some of my customers builds and only had one fail out of 3 builds . I think after socket 775 they started making decent boards. They use to be no frills kinda board but now are much better. From the reviews I have read they seem more reliable too. I personally use Asus for any of my builds.
I've had good luck with two I purchased. A 2-year old TA790GX I used in a build for my brother has proven to be a beast of an overclocker, too. I got his AMD X2 550 up to 3.7GHz at stock voltage on that board. The only bad thing with that particular board is I can't unlock the 550's severed cores on it. That CPU will unlock on two other Gigabyte boards, though. Biostar told me it's because the board has a single-plane power design, and AMD's quads require dual-plane power distribution.