I'm the only person I know who has one at the moment, and I'm 90% happy with it. There will be a system update coming in (rumor!) January or so which ought to fix several of the issues I'm not too happy about.
But the OS in itself is really solid. My Samsung Focus turns on very quickly, and I haven't had a hiccup yet.
If you can wait until January, though, I'd recommend it. By then all the major kinks should have been worked out. If your phone does fall apart, however, then definitely head out and look for a Samsung Focus.