I have one - it's not the easiest card to get to work but it is cheap. With the XL the problem some had with the Dream 331 chip is gone thankfully so I'm told but I have never seen the innards of the XL version. Mine has Dream 331 on it and has problems that require work arounds - my machine won't find the ISIS on restart and more troublesome a -42.2 dB random static background noise floor on startup that requires a reboot to eliminate - some of the machine configs I have used with the ISIS have had to be booted for about 25 minutes until they have booted clear with the regular background noise of -90 dB. This is clearly a pain in the arse !
latency is bad, works better with full Logic not the cut down version they ship. BTW I never received a single reply from the manufacturer re any of the problems.
Overall I'd say get something else like digi 001 ( I built a DAW with a P3 1 gig, digi 001 etc - faultless).
Cheers