Glad to find a fellow Charlotte Sometimes lover on this thread! Always a favourite book of mine as a kid (as was the song by The Cure). But I have to disagree that Ulysses is overrated. Brilliant, funny, original, sleazy, upbeat yet pessimistic at the same time: I love it. Tolkein fan here, too.
Overrated ones:
I'm with PPs on D H Lawrence. Contrived, stilted dialogue, plus he's inhibited about sex.
Daphne du Maurier's Rebecca. It's a poor carbon copy of Jane Eyre (which wasn't that great either) and has exactly the same plot.
Frankenstein (sorry). It's the literary equivalent of Bohemian Rhapsody and suffers from overexposure.
The Handmaid's Tale is a horrible book. Distasteful in the extreme.
John Fowles's The Collector (agree with PP on French Lieutenant's Woman too). Rank misogyny.
Aldous Huxley's Brave New World is really weak, badly-constructed, poorly-written literature. Come to think of it, that applies to Huxley in general and his nasty satires of his contemporaries.
Jane Austen's Emma. Slow, meandering, dull plot and the most unappealing heroine ever.
Ditto Bleak House. Esther Summerson is insufferable. As is her angsty mother. Ada and Rick are drips, and Jarndyce has strangely skewed motives.
Don Quixote. Repetitive and interminable.
Narnia leaves me cold. I don't know why.