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:
- There's a nasty bug in 1.3.5b where a new project's sample rate is always set to 8kHz, even if it says it isn't - you have to change the rate to something else and back again for it to be set properly at 41.1kHz, otherwise you lose lots of audio quality on a recording.
- Changing the input device always produces an error when you start recording, even if the device is actually working - you have to restart Audacity before starting recording.
- If Audacity complains about not being able to record from a USB (webcam) microphone, try setting the sample rate to 16kHz and—importantly—mono. Experimenting with arecord settings on the command line is a good way to figure out what your microphone actually supports.