Ardour's great. I've been donating $4/month for enough months that I probably could've bought one of the fancier “professional” DAWs, but why bother when Ardour does it all?
A couple friends and I started a band a couple months ago and we've started to use Ardour + a Behringer UMC1820 for some basic recording work; it's wild how quick we've been able to get up and running with it (to the point where our only limitation right now is scrounging up enough cables to hook up all our instruments to the UMC1820). Create tracks, pick each track's input, arm tracks for recording, hit record, hit play, and make noises. Our lead guitarist is more familiar with Cubase, but I had him try out Ardour and he's already putting together recordings; just had to point him to a couple manual pages and he was off to the races with it.
Curious to see how quick 9.0 will hit Ubuntu Studio (which is what we're using in our practice room). Cool to see Ardour finally get a dedicated piano roll window (presumably ported over from MixBus?); even though it's neat to be able to do MIDI editing directly from the main editor window, having the option to focus on a specific snippet will be handy. And the continued improvements with the new cue-based flow will be cool to play around with (and maybe work into live performances once we've got enough material down solid for shows?).