I've only done it in 3e and although it could be fun sometimes, most often it just became terribly frustrating. Yes, things were epic, but the combats lasting for hours, the broken disparity between AC and AB, spell DC's and Saving Throws and many more problems just made for a game that wasn't to my taste. Of course one of our DM's just loved it and kept on doing it...
He's DM'ing a low level 4e campaign now, but I can already see how eager he is to get us to into some high level, plane hopping, world shattering, god killing universe changing encounters. Hopefully that will work better in 4e...