I read this only a month ago, and it was the most enjoyable thing I've read in a long time. OTOH, I haven't read a whole lot of mainstream fiction.
I am not sure about the religious (probably Christian) overtone, though.
With "Heaven" in the title, I thought it would have had a much stronger Christian message or be "preachy" in some other way, but it has very little if any of that, at least IMHO. This was a pretty much secularized Heaven, even though Heaven itself is a Christian concept. I read it almost in spite of the title, and only because someone whose opinion I respect gave it a strong thumbs up. I recall God mentioned only two or three times, and that's enough for an agnostic UU who grew up in a Christian environment (okay, I realize that might not describe everyone here...)
While I wish I could say it was a beautiful book, it wasn’t. Not particularly enlightening or engaging since none of the concepts-heaven, interconnectivity/"the butterfly effect" etc.- were new to me or presented in an interesting way.
None were new to me either, but I didn't think any of those ideas were included in the book gratuitously, but rather they were all an integral part of telling the story.
Somewhere about halfway through I knew he had talked of having been married, and I kept wondering, HEY, I'm not reading anything about his wife, from what little I read he loved her dearly and she was a VERY important part of his life - what gives? But I kept reading (the pages were flying past, and it's a pretty short book) and soon had my curiosity satisfied. IIRC she was the Fourth Person he met.
I won't spoil anymore for those who haven't read it, other than to warn, be sure to have Kleenex (or other brand name...) handy when you get to the Fifth Person.