I have the e620 and I like using it. But if I were to choose all over again at this point, I might go for the pentax k-r. Reason being the e620 is a soon-to-be-2-years-old technology, so naturally if you're going for all the latest improvements, you won't find it in the e620.
K-r advantages:
- slightly larger APS-C sensor giving more usable high ISO pics
- video recording
- AF assist lamp
- higher FPS
- bigger LCD
- li-ion and AA compatible (once the battery adaptor is out)
e-620 advantages:
Weight with kit lens and li-ion battery should be similar for both, and both have in-body image stablization, shake/dust reduction. Price point should be similar as well, although the e620, being an older model, ought to be somewhat cheaper. Of course, if you intend to upgrade to their flagship models then lens choices would be an important factor as well.
Have you tried both cameras? The e620 has a somewhat different style of grip that some can't get used to. Ultimately it's your choice, since you might or might not care for all the additional new features. But if you're still interested in what 4/3 has to offer, why not look at the mirrorless offerings from Olympus and Panasonic?
*edit* note about the high ISO point. I used to complain like crazy about the high ISO output of my e-620 (when viewed from the monitor). But after printing in 4R, I realized it's not as big an issue as I thought, and so I'm a happy Oly user once again.