I don't think it's less highly regarded than any of the PT, at least not on this board. The prevailing opinion here seems to be:
-SW & ESB
-ROTJ
-Prequels
In that order. Personally, I would never consider ROTJ anywhere near as bad as the PT. But at the same time, I don't think it really stacks up against its predecessors, either. Granted, when I was a child it was easily my favorite of the three. My views have since matured, but I still find it very enjoyable (if somewhat cringe-inducing in a few places). ROTJ I like. SW and ESB I really like. The PT I utterly despise (aside from Frink's treatments, of course). And while I can't claim to speak for everyone, it does seem to be the majority opinion in the circles I run in.