Strangely enough, I like the show.
It's not exactly one of my favourites, but as far as the first season is concerned it's well written show with some extremely talented performers.
The second season started on a bad foot; the scripting was poor and I did not go for any of it, but I think it's getting better.
As far as "loving it or hating it" is concerned, the haters bother me so much more than the fans ever could.
People like the show for its quality. It actually IS well written and the songs ARE well done, whether they suit your exact tastes or not.
People who hate it just seem ignorant, or as if they're trying to hard to not conform to the crowd. It's not exactly "overrated" just because you don't like something, remember. The show deserves its fans.
The other crowd of people who seem to voice their negative opinions of this show seem to be homophobes; "Singing and dancing is for ******s what a gay show!!" and so forth.
Regarding the lip-syncing thing. To be blunt, of COURSE it's lip-synced and you'd be stupid to suggest any other way of doing it.
It's a professionally produced show, and having the singers perform the song in the studio, and then overlaying it on them performing the song in the scene, results in a HUGE audio quality lift.
Not to mention they hardly "badly lip sync," considering they're lip-syncing to their own singing and they're all more than capable of doing it well. Bear in mind they're probably actually singing during the recording too.