OK, so there are features other than DR that are actually important to you. Just checking
high iso performance
all of these are improved compared to the 5D2 and they are mostly the same to slightly better than the D800 (I think shutter response and metering are worse than D800 though as is lack of built-in flash (if this messes with T&S lenses on FF then perhaps it is just as well though) or intervalometer)
1. Anyway so far the one shot AF seems to be very good. Some have said for center point one shot it's no better than 5D2/7D since those were already great and some said it's definitely improved. I'm in the it's definitely improved camp. And the outer points are obviously world's better than the 5D2 outer points. Didn't try sports AI Servo yet. I read encouraging reports though. The AF spread coverage is better than on the 5D2 and it obviously gives you tons more options of every sort. It is nice to be able to pick a point exactly on the detail to focus on and not need worry about outer points not grabbing or having to slightly shift composition to bring a point in line or whether the outer points will actually ever grab focus or not, etc. And micro-focus adjustment now offers both wide and tele settings for zooms. They certainly gave it their all and finally held nothing back from AF. Great to get 1 series AF in a small body at last!
2. Top notch SNR at all ISOs, nothing else does better although a few, D4/D800/1DX(likely) do as well (the D3s also does as well but the resolution is so much lower so the 'grain' size is large and the detail low so I don't think it holds up anymore to the new best D4,D800,5D3). DxO says something like 2/3rds of a stop better than 5D2.
3. It offers the only video that is truly aliasing and moire free (if a bit rather soft....), D800 video has lots of color moire and a touch of aliasing and it has at least 1.5 stops worse SNR although it is a touch sharper, hacked GH2 is sharper and has zoom modes that are great although it has a touch of a digital look to it, everything else doesn't come close to 5D3.
4. General user interface is good, I know some people like Nikon UI but it always seemed non-intuitive to me, you can pick up a Canon never having used one before and be good to go in a minute, not with a Nikon.
5. General UI better than on the 5D2. You have the 7D's dedicated video switch, the histogram is outlined so it shows up even under the sun, the LCD looks better, the instant and exact zoom to 1:1 and back makes reviewing so much more efficient, dual review doesn't hurt, the rate button will surely save time under some scenarios, the liveview zoomed mode is much crisper than the weird line-skipped mangle in the D800 (not sure why they did that since the D800 should be able to do it better as their D7000 does), might be forgetting some things or not had time to come across them yet.
6. The grip is grippier.
7. The build is better, no creaking doors and such.
8. No ugly banding in darker parts of very high ISO shots, it's all gone even up to at least 25,600 (as high as I've looked so far). 5D2 could get ugly banding in the darker parts of very high ISO images and make them look unnatural and objectionable at times, 5D3 is free of that.
9. 50% faster frame rate than 5D2 (or D800 in FF mode) and shorter mirror blackout and shutter response times make it feel snappier so it's certainly better for action, some critical improvements there! D800 is even a bit snappier still for response but its 6fps are only with grip and DX mode (5fps without grip at 25MP), when you can get close enough to frame as desired the D800 will suffer for noise compared to the 5D3 at high speed by quite a bit, otherwise, when fully distance limited, it would arguably do better since you don't waste storage space on empty outer area of frame and it has more reach due to higher photosite density and if you leave the grip behind and suddenly wish you ahd the speed it's 4fps all the way.
10. Very high ISO DR is improved a bit from the 5D2 although the D4 has it beat in that regard, nothing else really does though, D800 is similar although a bit worse at the really high ISOs.
11. Has no low ISO horizontal banding (although still having all the vertical you still notice banding anyway, for the shots where that stuff could appear).
1. The low ISO dynamic range considering what else is out there and they actually went backwards(!) (if only trace) from the 5D2 after three years, has some of worst read noise per photosite at ISO 100 of any camera they've made since 30D era, shocking. This is one part where the dropped the more than I or just anyone ever remotely imagined. Kinda sad really.
2. It's perhaps a minor thing but that just makes it all the more ridiculous but they still have crippled autoiso (although not nearly as crippled as on the 5D2 which is utterly useless, other brands get it right at all price levels though and don't play such games) since still no EC in M mode and for Av they made the maximum minumum shutter speed limited to an absurd 1/250th (BTW there is zero technical reason for this, it could be whatever number the want). Could be fixed in firmware with maybe one line of code altered.
3. No crop mode for video (and the 2x2 sampling might mean they need to do less blurring and make it sharper) (no worse than 5D2) and no focus peaking and zebra stripes, supposedly still a cheap hissy audio amp but I didn't listen myself yet not sure (some other brands get it right at times), all rather a shock. For 3 years and with all the acclaim the 5D2 brought it's really pretty ridiculous. Thankfully it seems ML will work so 2 of 3 should be fixed by that. We just have to hope Canon will add the sharp 2x2 C300-like sampled 1920x1080 1.6x crop mode.
4. Can't change focusing screen (it always seems weird to me when you are shoot f/1.4 and the entire scene looks in focus through VF when only a small fraction is, at least the AF is better so it's not quite such a risk to trust it is doing what it should be and the point spread is wider and the outer points work much better though) (most other options get it right).
5. Reach is slightly weak for wildlife (no worse than 5D2 though) (only the D800 is appreciably better for FF) and max detail can't match D800 for landscapes. I could live with it for now if they truly couldn't go beyond 22MP and keep 6fps, it seems they could've bumped up a bit more though and it's a bit troublesome that they didn't at least improve the DR then, if they did that then low ISO would've been improved even without more MP.
6. No f/8 AF (although if it improves it otherwise the trade off is worth it IMO, although if the D4/D800 actually is as good, and I see reports going both ways, then you do wonder a bit) (no worse than 5D2 though) (only older 1 series and newest higher-level Nikons can do it).
7. Still has as much vertical banding at low ISO as the 5D2 (only the 1Ds3 from Canon, I think, is free of vertical banding at low ISO).
8. A bit higher in chroma noise and can distinguish a bit fewer colors than the top Nikons since they had to cheat the color filter a little to get to the record tying SNR.
9. SD slot is crippled to be very slow, a bit odd for a $3500 camera which will be used by wedding photographers a lot. I don't think it will be a huge deal for what I do but it seems a bit of a nasty cripple for wedding shooters and it's pretty bizarre, they get stuck with a very small buffer and slow clearing, very odd, seems like a penny pinching cheap decision. For me, at the moment at least, I don't think it matters much though.
Certainly it's much nicer than the 5D2, much better usability, a better and more fun to use camera that can handle, with aplomb, a wider array of shooting circumstances and it has somewhat better low light image quality that takes it to top of class for that and video without moire/aliasing disasters plus what looks like 2 stops better noise than the 5D2.
The low ISO DR is a huge shame though as are the mysterious absence of a few video features and it's slightly surprisingly that this long after digic 4 that 22MP is the max for 6fps.