I noticed recently that if one sets the upload speed to about 20 KiB/s it will take about 3 more KiB/s more than that; this is especially true when you're on torrents with a huge number of peers. If you have more than one torrent seeding and forget this factor in calculating your upload speeds you can saturate your connection pretty quickly.

Otherwise it's my favorite client. Plain, simple, no-frills. Just does what it's supposed to.