I've only had a few hours, but am really digging it.
The interface, set up, and options are as good if not better than I've seen in a sim. Setting up controllers and binding keys is a pleasure. Adjusting graphics settings for FPS optimization can be done on the fly, with immediate feedback (with Fraps) on the paused screen on which the menu is superimposed.
Flight model on expert feels good-takes work to hover and land well. I don't think the Vortex ring is modeled (Edit: this and other FM fine tuning coming in a patch).
I found a graphics vs. performance (very) sweet spot on my machine (e8400@4.0/hd6970). Check here for optimal set-up: http://forums.bistudio.com/showthread.php?t=126178. Sky, clouds, and weather are as good as I've seen in any sim. Saw a double rainbow near Seattle! Okay, it was only one rainbow, but still.
I can tell training and missions are going to be really immersive and fun. Tried the first time challenge (a low level run through the forrest) and had a blast. Collidable trees-yeah buddy! The modder community are going to have a field day with this one.
Basically, this is my immediate further: (i) flop down on the couch, fire up PS3 Battlefield 3 till I pass out; (ii) if have some energy, move to the PC for some jump-in-and-fly helio action; (iii) if have a little bit more energy, skip (ii) and go directly to DCS.
Overall, I'm glad I bought TOH.