1: BIG. Not a little big. BIG big. Just shy of not fitting in my Antec three hundred case big. Part of the card up into the drive bays big.
2: Quiet. Very very quiet. It CAN get loud, but it hasn't done so while gaming yet. It's on the same level as my GTX260 SOC, which is extremely tolerable until the fans ramp up above 60% or so.
3: Temps are much cooler. Loaded temp on the GTX260 could hit 92C... 680 is tons cooler. Idles at (started at 30c, ramped up from there. After exiting gaming, etc, it's back down to 35-36c... ambient should be at or around 25c) (remember, this is also inside my fairly crowded case which I HAVE optimized for cooling as best possible)
4: WoT now running at 120 fps base. Need to fuss with my CPU and see what that can do. (WoT is fairly cpu limited for some reason).. my cpu currently at 3.6 GHz with no turbo enabled. If you'll recall from my previous threads, the GTX260 ran World of Tanks at a rough base of 70 fps in this computer, so basically added about 40% to the framerate by swapping up, with no other changes.
5: Diablo 3 doesn't display framerate atm. Getting a zero. Expect it will be quite high.
Reasons I bought it? GTX260 getting long in the tooth. And tbh, glad to get that fireball out of the case. It was made to work at those temps, but it made everything else that much warmer. Plus I was getting occasional gpu resets which I'm attributing to age + temperature... although at least a couple of those resets occurred at the desktop. The SOC units are rather massively overclocked... 576 MHz base speed, and the unit we have came from the factory at 680. It's actually faster than a stock GTX 275. Also throw in DirectX 9/10/11 compatibility and performance and my relatively recent upgrade to a 1920x1200 display, at which level the 260 was starting to suffer.
Reason I bought it over a stock GTX 680? Massively overbuilt. Backplate, oversized fans, extra copper, 'military class' msi branding. Basically, quality, quality, quality. Plus the extra clocks right in the bios don't hurt one bit. I've never ever ever owned a card this far ahead of the curve.
Worth the money? A relative statement. The card is worth 600$ as much as any gpu might be. Basically, it's a toy. A toy that ought to last me two years, but a toy nevertheless. If you don't want to spend 600$, but might consider spending 400$, take a look at the GTX 670 Power Edition, also from MSI. Same concept as the lightning, but on the 670 framework. Even uses the same backplate. Fans aren't quite as big though...