What you want in a movie like this, are 2 things: firstly a gory bloodbath and then secondly either great humor or great action. The 2 best examples from recent years are "Piranha 3D"  which is both hilariously funny and contains some of the best and goriest death-by-fish scenes ever made, and "Deep Blue Sea"  which is a bit more serious (yet still rather funny) and has some great shark action and again lots of blood and teeth.
The Meg is sadly a PG-13 rated movie with almost no blood (a human arm in the water doesn't count.) How the hell can an enormous pre-historic shark with teeth all over it's face raid a beach with hundreds of swimming people without any blood or gore being shown at all? It makes me sad. The lake party scene in "Piranha 3D" is what you want to aim for here. They even copied the basic story from the same movie, having the Shark come from deep below.
The movie has some terrible humor. Maybe the humor was directed at small American children or at old Chinese people, I really don't know, but it is cringeworthy as hell. Of course there's also an annoying kid in the movie, a lot of clichés and a typical Asian movie love story where nothing happens at all. Jason Statham is obviously being himself, the rest of the actors are mostly a bunch of annoying clichés. The Megalodon looks a lot like a big rubber shark, where the sharks in "Deep Blue Sea" looked pretty damn real to me.
You may be curious and you may like shark movies, but this one just isn't worth it. Wait for it to end up on Netflix, it'll fit in perfectly well in their shitty movie selection.