In my experience, it isn't worth messing with. On my T41:

1) Ungodly slow. Even when tweaking the video driver settings. 8.04 was much faster.
2) Pokey wireless network transfers, when you're able to connect. WICD works pretty well, but it doesn't fix all the problems.
3) KUpdateManager (or whatever it's called) is ungodly uninformative. It has 5 updates marked as "blocked" but tells me nothing about them. Trying to update the repository lists or changing the update server location causes Python 2.6 to crash before the list finishes (it hangs at 103 of 113). There's no clear way to run Synaptic instead. It seems impossible to do a full update successfully, at least with a GUI.
4) There's no clear way to install KDE 3.x instead.
5) Konqueror is extremely unresponsive with 5 tabs open and its memory consumption increases for no apparent reason. Firefox is more stable, but is still slow and a RAM hog.
6) 200 MB of swap is being used with 1 GB of RAM free, for no apparent reason.
7) Something seems to be grabbing 100% of the CPU and making the CPU temperature rise excessively, but it's not clear in the process list. Killing Konqueror takes care of most of the problem and unpins the CPU.

Etc.

I'm trying to install Gnome on it at the moment. Perhaps that will make it bearable before I transfer everything important off it to try Debian. I might also try Mepis again since that usually seemed to run well on it (and it is still on KDE 3.x).

Cheers,
Scott.