Once you get your head around how Audacity works, learn the shortcuts (ctrl-mousewheel to zoom, ctrl-click to start playing at a certain point, J/K to move to the start/end of the track, Shift-J/Shift-K to select from the cursor to the start/end of the track), find the audio tools (envelope, time-shift), get it connected to the right audio inputs and outputs, and are lucky enough to have a system on which it doesn't crash often, it's actually surprisingly good.

A couple of things to watch out for:

Audacity uses PortAudio for cross-platform compatibility, which means it can't use PulseAudio directly, but it's happy to connect to JACK for inputs and outputs. You can use this to record audio from Flash players, for example, or anything else which uses PulseAudio for output.