The original Bittorrent client failed to impress me & I had to switch allegiance to Azureus, a Java-based client that has won Sourceforge.net's Community Choice Award (2006) for "Best Overall" Category.
This client comes with its own share of problems. The interface looks amateurish & closely resembles that of the Eclipse IDE. Launching the client immediately throws up a series of error messages. Overlook them & the product works just fine.
The Bittorrent protocol, though, has not been too impressive. My biggest gripe is its slow speed.