It's been pretty good so far, set up is really easy, launch is pretty good although a bit sketchy if you aren't confident with a kite - it takes a while to fill with air and you need to be pretty aggressive on the bar until it's taken shape, but it is nice and quick to put in the air and I've been the first on the water every time I've taken it out. I guess the self launch issue is the same for LEI's, except with the Flysurfer it's your only option. Anyway for a 12 it looks huge and it's a little slower than my 12 switchblade 3, but for me that's cool - I'm trying to be wakestyle and so long as it pulls I don't really need it to move that quick. It really does pull too, it hasn't got me out any earlier than my switchblade would have, but I am better powered earlier, so I've been out in 12-13 knots doing my only trick (back to revert) really comfortably. It's also really good for messing about on a skimboard (or any other strapless board i guess) because it's soooooo floaty even in light wind, great for learning strapless airs or transitions.
In high wind it is ridiculous, I've been on Switchblades almost exclusively for 2 years so the difference is phenomenal, it's really easy to hold down and jumps are massive, especially for a 12m. Been way higher on this 12 then I have on my old 8, and even had to loop it on the way down which I didn't think would be possible. It's so big that even when it looks like it's in front of you, one of the wingtips is above your head so its floaty on the way down pretty much no matter where it is in the window - so long as you keep it moving.
I should probably add that I don't think big air is the coolest thing in kitesurfing, and I should really have been on an 8 keeping it steezy... buuuut it was a sweet session! Definitely fun when you aren't keen to get spanked.