I've found the only real drawback is that it makes it hard to recommend shows to people. I couldn't tell you what channel most of the stuff we watch is on, hell I've lost track of what days most of them air on. The other problem, if you can call it that is you miss announcements of upcoming shows since you all but stop watching commercials.
My favorite feature is the wish list, we add obscure/old stuff all the time and it's a bit like Christmas morning when you look at your saved programs and find a gem you haven't seen in years got recorded got recorded when you weren't looking.