So here's my rundown of Acceleration after a week's hard use. For anyone who's on the fence about it, read on, I'm going to give you a comprehensive list of the plusses and minuses.
Accelerated (the good stuff):
-DX9 Performance is definitely up. New autogen batching etc worked well.
-The F-18 is great overall. The hud kicks ass, sooo nice.
-The P-51 is there. That's all. I don't like em.
-The EH-101 is there. See above.
-The water rendering options are waaaay better. Low 2.x is just water. Mid 2.x is reflected clouds only (yay), High 2.x reflects clouds and terrain but not autogen (yay!), and Max 2.x reflects everything. That's how it should have been set up from the start.
-Multiplayer Fixes, LOTS OF EM. Canopy/exit animations now show correctly in multi, as do airbrakes and tailhooks. Awesome. Been waiting for that for six years. Landing gears no longer get out of sync when someone appears to pass through terrain. Wicked.
-Multiplayer lobby screens no longer jump around like a jack russell terrier. You can actually select a game or add people to your contact lists without feeling like you're playing whack-a-mole. Nice one.
-The Missions are great, assuming you can get the EH-101 which is used for most of them to behave like an actual helicopter (see below).
-Smoke effects no longer detach from your aircraft at low altitude.
Decelerated (the not so good stuff):
-DX10 is a disaster for most people, myself included. Could be FSX, could be drivers, could be Vista, could be all of the above. Whatever it is, help is needed urgently.
-Flashing clouds. It doesn't happen often but clouds aren't as stable anymore on quick track-ir movements.
-Landclass issues. I've seen fields of crops on the PEAKS of the alps, not in the valleys. This is with default landclass data, so either Sp2 models some extremely ambitious farmers or something's seriously porked there.
-Sloping water/rocks bug is back. They fixed this in Sp1, but the 'Thames river bug' is back in Sp2. That's going to put a small dent in my Iceland vector project.
-Vsync is no longer available through the fsx.cfg. It can be forced in the driver in DX9, is totally hosed in DX10. That's a DX10 showstopper for me right there. No Vsync no play.
-All sorts of texture problems, even on correctly compiled pure FSX aircraft. Most of these can and will be fixed, either by users or developers. I'll fix the ones I care about.
-Light effects on the external models can cause all sorts of weirdness texture wise in the VC. On my SR-71 the afterburner lights turn my artificial horizon into a mirror...umm... Haven't even begun to figure this out yet.
-The EH-101 flight model... is.... crap! To be remotely flyable it has to be run on lowest realism settings. It wanders, the engine surge, hovering is hopeless. Keep an eye on the guys at Hovercontrol, my bet is they'll fix it before the developer can.
-F-18 Afterburner effect is a cartoon in motion. I can and will fix that. The rear landing gear is ridiculously high and out of proportion to the chord line of the aircraft. Again I think I can fix that. Just what photo were they working from I'd love to know.
-The P-51 sometimes catches fire in multiplayer for no reason, even with engine damage disabled. It also has some sound issues when two of them are in a session.
-SP2 multi is not backwards compatible with SP1 multi. Doesn't bother me, but the lobbies are looking a bit like a ghost town at the moment, we'll see how it goes.
That's it for now. Overall I like it... I think. ;)