Depending on the "flavor" of DSL, it can be good and bad. ADSL, or Asymetric DSL has a different upload and download speed, much like cable (which has an upload cap of 128Kb/s). SDSL is Symmetric DSL which allows the same upload and download speeds.
If you expect to upload a lot of stuff, DSL is usually better. If you live in a very high-tech neighborhood, your cable will be shared with your neighbors. Usually not a problem, but some people get major slowdowns during peak periods (7-10PM). DSL is guaranteed bandwidth (for the most part) and will perform more consistently, but much slower than cable.
I've got @home cable. When I find a fast site, I can often download at 300KB/s. a 256Kb/s cable maxes out at about 25KB/s. Yet, that same DSL (if it's SDSL) will upload twice as fast as I can.
Cable is great, in general. I've very happy with mine and it's been very stable. I rarely have any slowdowns, but I don't live in a real high-tech neighborhood.
- G