I read mostly scifi books and some fantasy.
Stuff that's been mentioned on this thread before that I've read:
Twilight: First two (Twilight and New Moon) stank horibbly. Last two (Eclipse and Breaking Dawn) actually decent. Series 2/5.
Eragon: Read them all to date. At their best when slash-boom action, and the last 75-ish pages of Brisingr- brilliant. 3/5
Agatha Christie's stuff is classic (best selling author of all time- hey, who knew that?).5/5
The Ender novels: Best scifi that doesn't involve the fate of the universe or massive body counts.4/5
A few personal favorites:
Dead Beat (Jim Butcher), Best Harry Dresden novel, absolutely hilarious, and very good plot.
American Gods (Neil Gaiman), If you're under 21 do not read this, very adult, and maybe the best novel I've read in a very long time.