I have for about 2 years, with their cheapest shared hosting package. It was surprisingly stable and fast compared to most of their direct competitors that I've tried. They probably some cache system in place, which would explain the server speed.
One major downside (or maybe upside from a small site owner's perspective) is that they have a strict limit on database size (100 or 200MB from what I recall), and that, because they're totally procedures run, if you fall through the cracks, you might as well talk to a wall.
