Audacity has a number of good and primary functions. Many Nyquist plugins as well as some VST plugins are available and work well with Audacity. The Linux port has a bit more flexibility than the Windows package I believe. I can't speak about the Mac pack, but have no doubt that its every bit as functional as the others.
Some folks use Kristal or another sonic package to record and then run it through Audacity. I use Audacity to both record and mix multi-tracks. It's exceptionally easy.
No, it doesn't have all the gizmoids, bells and whistles and pretty graphical popup interfaces as say, Magix or others. And really, how many of those gizmo things can you use at once much less remember where they are on all those menus.
Audacity sure does one good job without a lot of fuss. And I can *see* the Record Button!
Les