I use it with a MacBook Pro 2.8 Ghz/4Go ram and speaker Adam A5
Cf thomann or tcelectronics.com for details.
The drivers are very stable under Mac, no problem for now. I go with my guitar in Live8 Amplitube2, nickel and nothing wrong. I 8ms latency, I expected to have less (the IO2 was 9 ms latency), but I'll try to get buffers. The app comes with is cool. It can control the DSP effects built into the card (reverb, compressor and equations). Practice but I have no use because I live in while vst but the idea is good to correct the sound (almost) upstream.
The only thing to blame him is the length of the included cable (1m), I had to buy another in order to make the right laptop. There is a firewire 400 to 800 (fortunately for that matter), not stupid!
The plug installation cd, install and play, not bad =). Everything is updated automatically.
As said earlier, I mainly need additional inputs and I "flashed" on the twin impact. Very pleasant to use, I do not regret my purchase (so 500chf € 345). I do not use the DSP effects for the moment but why not.
EDIT (September 8, 2010): Still nothing to say except that eventually I would still just a tiny outlet for the metronome, I did not think I'm a little pissed off now. Count out the number of inputs / outputs you need ...