This is so true. I built my first set of wheels about four years ago, and since then I've managed to find excuses to build five more sets. It's one of the first things I want to do when I get a new bike now.

I was nervous about the quality of my first set. I spent hours obsessing over the spoke tension and truing and still didn't get it perfect. Eventually I had to put them on the road. Since then I've put about 6000 miles on them, including some mountain bike racing. They've held up great. The only problem I've had was when I managed to put my chain into the rear spokes (chain too short + big/big gears = bad). Even then, with one cut spoke and a bunch more damaged, the wheel held enough to get me to work and back home (it helped that it's a disc brake wheel).

The biggest upside to building your own wheels is that you get free lifetime ride-along support from the wheel builder.