Yes, I'm still using and enjoying my iPad1. Not only does it run well, but the battery is as long-lasting as before; if it has lost anything, it's not very noticeable. It's funny how once the iPad2 was announced several people decided they had to sell there 1s and upgrade to the 2 (as though somehow the 1 just wouldn't work well anymore).
Of course, Apple wants everyone to upgrade each and every time. However, that is silly. Since the iPhone's pricing gets subsidized and has more significant upgrades, it makes more sense.
For me, since day 1, I wanted a higher resolution iPad. So, if the next version has this feature, I will upgrade.
At present, I'm still really enjoying my 1.