I have a Gigabyte 88 something or other...it isn't an FX board, it's an mATX and it was $50. I have an 860K at 4.4GHz at stock voltage with the stock cooler.
My overclocked CPUmark performance is basically level with an i5-4570S and slightly lower than an i5-4670k. Obviously overclocking the i5-4670k turns the tables considerably. Both the i5's use almost half the power at idle and about 1/4 less power under load.
But we're comparing a $70 CPU to a $200 CPU.
This is the first AMD system I've built in almost 10 years and I'm not disappointed. It just seems like ever since the Core 2 (and especially the Core i) came out, AMD didn't have anything relevant for the price in the $100 bracket, but after AMD price cuts and Intel slowing down on IPC improvements over the years, AMD is relevant if it is cheap enough.
Stability and compatibility all seem fine. I run the system 24/7 with monthly reboots. It's my gaming PC with a GTX 770.