I recently purchased one. It's my first sampler, so I don't have anything to compare it to, but I think it's great. It does everything I wanted it to. The effects are pretty good and it's really easy to use. I've had no problems with it. The only annoying thing, is that it doesn't have enough internal sampling time, so you have to buy some Smartmedia cards (around $20 each for the 8mb). I would definitely recommend it, and from everything I've read, it seems better than any other sampler in it's price range. If you want to you can check out these sites for full reviews:
http://www.sospubs.co.uk/search/query.asp http://industrial.org/cgi-bin/ms2/moron/gearbase?device=SampleTrak+ST-224