I agree with the last 2 posts, one of main noticable improvements for me besides the higher res screen of course is indeed the speed difference in the time it takes to load web pages, I went from a iPad 1 to the iPad so perhaps it's more noticable than when going from the iPad2... In comparison tests I did our iPad 1 was only halfway across the loading progress bar when my iPad 3 had finished, so quite a big improvement in web loading speeds... infact that was one of the 1st things I noticed when I first had the iPad3.
The iPad 2 may already be faster in that area already over the iPad1.. I don't know as I never had a 2. The screen on the 3 is obviously better, and I suppose I notice it a little when I'm using the wife's iPad1, However, I still think the screens on the iPads 1&2 are still pretty good, and are far better than many other devices out there. I doubt I would have upgraded quite so quickly to the iPad3 if I had already got the iPad2.
Everyones circumstances are different.. TBH. I like my toys, I'm in late sixties and probably have more money than sense, so I likely may have still got one anyway...lol, but I did'nt need too much of an excuse, as my wife tended to use our iPad 1 a lot, so TBH a second one was useful to us anyway.. so I treated myself... your dead a very long time, so these days I'm more inclined to indulge my whims.. thankfully iPads don't cost as much as my cars..lol
So.. should you buy one...IMO If your in a situation where the small expediture on a new iPad3 is'nt going to make much of a dent to your finances.. then yes go ahead and treat yourself, otherwise stick with the iPad2 until you are in that situation.... the iPad2 is still a very desirable and useful device.
I note you have made 148 posts so I assume you have the iPad2. However If you don't currently have a iPad at all, and it's simply a choice between the 2 or the 3, then that is much easier to answer.. get the iPad3... it's worth paying the small extra for, and I suspect being the current model will hold it's value better.