I recently went through this along with my wife. We wanted apple as we have iPhones so we can share apps between them and each other ( the latter is legal for those not familiar with Apple).
I took my camera to the apple store and asked them if I could transfer photos using the camera connection kit. It transferred raw and jpg no problem. It also displayed the raw and jpg perfectly. In fact I reckon it is the fastest way of reviewing raw which is pretty much all I shoot.
We compared the iPad 2 and 3 for image quality. The iPad 3 is slightly better but not jump out and slap you in the face better for looking at dslr pics unless you zoom in. For other requirements it may be a lot better. If you just picked up an iPad 2 without comparing it you would be impressed. I would have got a 2 but they didn't have 32gb at the time and I concluded 16gb was too small.
A week later my wife got an iPad 2 64gb. We have compared them side by side with the same images and both are good. If money is no object get a 3. If you're on a budget put any spare cash into memory.
Either of these iPads have made all of our pics plus the sites we view on the web look ten times better. Pictures i thought were average now look great. Maybe it just highlights the limitations of a pc screen.
Another thing to consider is calibration. I recently bought a spider to calibrate our PCs. You can actually use it on the iPad of a fashion. Essentially you can view images calibrated using the spider app. This would be handy for showing portfolio or "as" printed stuff.
Yesterday I bought the apple tv unit. It's a little box that plugs into the tv and allows you to mirror your iPad or iPhone to it, including images over wireless. We can now sit on the couch and review our pics together on a hd tv.
In summary I'm really pleased with the iPads (1 and 2) and we got them primarily for photo related activity.
The other thing I intend to use it for is reviewing images in the field when I won't easily get a chance to go back and re-take it.
One thing to remember. If you transfer from PC/MAC to iPad it will compress the pics a bit. I still have good quality but not original quality. If you want full quality you need an add on app to transfer the files. I got photomgrpro (I'm sure there are others) to do this although normally I'm happy with what the iPad does. This is one of those "apple knows best" things which does annoy me coming from the PC world.
Hope this helps.
Sent from my iPad using Tapatalk HD so excuse all the errors