The biggest problem I see is some show scheduled at, say, 20:00 followed by the same show at 20:05; the first records, the second doesn't, and you miss most of the show. This is something that could be fixed automatically.

At least, that was the main problem until a few days ago when, I've just discovered, all my TiVos simultaneously stopped importing data -- they connect and claim to be fetching it, but it completes too quickly and there's nothing in the guide beyond early Sunday. Is there a problem with the server, or has something expired on the TiVo? Network stuff not in the "Now Showing" list any more, either...