A longish but quite easy read: a charming and unusual mix of time travel paradoxes/free will versus determinism/co-incidences that aren't etc, coupled with a non-soppy love story. It handles some of the potentially dodgy situations very sensitively (eg when adult Henry visits young Clare). I'm not sure I'd write the ending the same way, and got to the point where I almost didn't want to read on in case I didn't like it.
Now that I've read Kurt Vonnegut's Slaughterhouse Five or the Children's Crusade, I realise the central idea of an occasional, accidental time traveller is not hers. Although that detracts from what I thought was her originality, her book is very different, and still an excellent read.