It's been awhile since I read "Hail Mary" but Jim Knighthorse is just the same as ever: big, egotistic and ridiculous. This was a fun read, though not as funny as previous books in this series. It's a little repetitive and the characters all sounded the same at instances, which sort of derailed the humor for me.
The case Jim is working on was interesting and not as predictable as it first appears. Hollywood is crazy is a pretty good summary of it. All the dots connect together with no giant leaps of logic, and Jim even gets to solve some other cases along the way.
It does get dark. Jim's not always a nice guy, but only to the bad guys. The resolution of the case is pretty gruesome but thankfully doesn't linger over the details longer than necessary.
I don't think Jim would find the name Christian Grey sexy though. We see in this very book just what Jim does to rapists, and from everything I've heard about the 50 Shades books, Grey is pretty much a rapist, or the next worst thing.
I haven't read any other books by J.R. Rain outside of this series except for "Silent Echo" which I found did not live up to its potential, so this is the first time I saw any indication that all his works are related to each other. At least it's not necessary to read all the other books to appreciate this series, but it does explain the small paranormal subplot with Jack that runs through the series. I wonder if Jack shows up in Rain's other books. I'm not interested enough in vampires to find out though.