I am using it in OSX on a dual 1ghz G4.
If you're a mac user I am going to copy and paste a recent thread I wrote at Sonikmatter about it. If you're on Windows, the news is a different story because Yamaha is a little further along in development on that platform than on the Mac.
I own one, as do most of the folks on that board.
Many of us have the 01X running nicely with OSX.
What computer are you using?
As of 11/14/04 here is what does and doesn't work on the 01X with 1.02b drivers and OSX.3.5
*24 channels of mLan audio into Logic 7 on OSX
*2, 4, 6, 8 channels of mLan audio Outs to the 01X (anything more will strain your CPU)
*Control Surface / Logic Control works, the only complaint I've heard is not being able to write markers with the 01X. The transport works great (especially with Logic 7 where you can adjust bandwidth allowed for MIDI). Automation is a breeze with the faders and yes, they follow automation as well.
*MIDI ports are working (there is a little fix you have to do to stop odd sysex info from the 01X coming into Logic - very easy to do.
*On board FX are useful when trying to save CPU in a bounce (eq's, compression, reverb on the 01X sound good, just like any other Yamaha mixer).
*Included plug-ins have just been updated for Logic 7 and AU validation - used them yesterday, they are working.
*As I stated before - the less monitoring channels you need to use the easier it is on your CPU. If you are doing a stereo mixdown and using Logic automation, you don't need more than 2 channels anyway.
*You can't have multiple mLan devices hooked up at one time yet (ie. the i88x - this is coming in about a month Yamaha tells us)
*You have to reconnect to the 01X every time you boot your machine, it isn't persistent. Not a huge hassle.
*Playing with devices on the firewire line will loose connection between 01X and computer - but this is true for most firewire audio equipment (ie. hot swapping a firewire harddrive in a the middle of a Logic session is a bad idea).
*Studio Manager (a graphic control for the 01X's mixing capabilities works ok, but not at the same time as Logic. One sort of goofs up the other.
All in all, the 01X is an amazing machine. The community of guys over at 01X are awesome and Yamaha actually reads the boards (even if they don't respond as quickly or as often as we'd like sometimes). I am up and running with the 01X because of those guys' help and am much in debt. I have to say I am pleased with the 01X. Our biggest gripes are that the CPU performance with mLan needs to be better, we'd like to hook up multiple mLan devices, and we'd like a graphic patchbay for mLan that our windows counter parts are enjoying.