Yoshitomi's Blue Drop stories have always been interesting. The original manga was a beautiful set of yuri stories. The anime was sweet and touching. Tenshi no Bokura, on the other hand, is just plain weird.
It's hard to get a bad story with the set-up being that the Earth has been conquered by sexy lesbian aliens. I wouldn't say Tenshi no Bokura was bad either, just extremely strange. Whereas the other Blue Drop manga and the anime focus on relationships developing between the Arume and human girls, this one seems to be an effort to tell us what's happening with the guys under the Arume rule.
The result in a manga full of stuff straight out of fringe fetish hentai. You have yuri, male-female transformation, cross-dressing shota yaoi, and whatever else the author wants to throw in. It's kind of odd but the manga is full of sex and nudity to the point where it might have been better as hentai.
Yohimtomi's art is nice as always, especially in the yuri scenes. His plot seems a little harder to connect with though. It's just strange, seemingly going all over the place only to end up going nowhere. I don't really know what to make of it as a whole.
If you're looking for a manga that is truly unique and bizarre read this. If you're looking for something deep or something great go read something else.