I'll be very interested to hear what you think. FL Studio has a pretty huge installed base and a lot of dedicated fans. I initially found it interesting, but it was more EDM/MIDI oriented. Wwhen Ableton Live appeared, and I could ReWire it with Sonar when I wanted looping/MIDI/hard disk recording, I felt that combo had much more potential for what I wanted to do.
I keep current on all the major DAWs (Studio One, Ableton Live, Digital Performer, Cakewalk, Cubase, Pro Tools) but have not kept up with FL Studio. I've been debating whether I should spend a couple weeks learning it so I can incorporate what it does into my writing. So I'll be very interested to hear if you love it, or go "meh."