The titular Shazam and has alter-ego Billy Batson feel like completely different characters. This is not unheard of for a superhero by any stretch, but when accompanied by a change of actor, it's a pretty jarring situation. I also have a hard time figuring out who the target demographic is with this thing. Seems all over the place.
But! at the end of the day, the most important question is "Did I enjoy Shazam!?" and to that the answer is still somehow yes. Probably the best that the DCIThoughSheWasWithUniverse has to offer (with the glaring exception of Wonder Woman).
Final rating:★★★ - I liked it. Would personally recommend you give it a go.