My first thought was to compare it to Doctor Who's Weeping Angels, but a gay Somewhere in Time is a much better comparison. There's enough different that that's not a spoiler if you've read the book or seen the movie though. If you haven't, the basic premise is someone gets sent into the past and falls in love with someone there, resulting in the dilemma of staying there or trying to return to the present. It is a very engaging story, with some pointed commentary on racism and homophobia, both in the 50's and now, and the dilemma makes for a really difficult decision - regardless of who stays or goes, someone loses someone they love.

The only low points I found:

1. When he gets there, the reaction to his actions are...highly optimistic. On the other hand, if they were realistic, this would be a tragedy instead of a romance, and probably a short story as well, so I'll give him a pass on this one.
2. His best friend plays a large part in the beginning, but is invisible afterwards. I think she should have had more of a presence.
3. I can't say much without spoilers, but I think what happens after the book ends may not be ideal. Again though, the book is much better the way it's written, so I have to overlook that too.