Contrary to what most of the folks here have said, the UI for Bias Deck is absolutely superb for what it was designed to do: multi-track audio editing. It was NOT designed to take audio tracks from your hard drive and edit them. That's simply not what multi-track software is for, and if that was what you are trying to do, you should not even consider Deck, Logic, or any other piece of multi-track software, and consider an app that is more suited to post-production editing like BIAS Peak, Sound Studio, etc.

I have yet to see any other multi-track audio app that was designed as well from a usability perspective as BIAS deck. That's not to say that I couldn't make dozens of suggestions to make it better... things like clip levels (get a copy of Discreet Cinestream to see what I mean), post-effects for 5.1, multiple effects-only busses with user-controlled routing, etc., but on the whole, it is fairly friendly to work with.

However, my praise stops at design. When it comes to implementation, one word comes to mind: stability.

Deck was rock-solid in Mac OS 9. Unfortunately, it didn't make the transition well. From the near-constant (and completely bogus) "disk not fast enough" errors to hanging every couple of minutes on dual processor machines (disabling one CPU "fixes" the problem), this application has been an absolute nightmare.

As much as I'd like to recommend Deck, I can't. The Mac OS X version is just not ready for prime time....