I'm a member of my local cinema's club thing, and last night they did an early screening of Shazam! just for members. So I went along and I'm pleased to say it's a pretty satisfying movie! I'm not a big Shazam reader (I've only read the New 52 TPB and another one which was a team up with Superman. Other than that, I've probably only seen him pop up in crossovers) so I couldn't tell you how faithful it was or not to the comic book... but still. If you're looking for a pretty good DC film you could do a lot worse!
Don't ask me for any spoilers cause ya ain't gettin' none!