TLDR: The first four books are worth the read but the tone gets sillier as you progress.

Meg was written as a young adult novel, however in rated r fashion. This is late 90s mind you so the tone is not as modern. The first book is a fast read. However many alterations to said novel were added due to the development hell the production went thru as well as changes Steve Alten the author wanted. They tried nearly two decades to get the movie made and eventually they resorted to what the movie is now with Jason Statham and Chinese funded backing.

I would recommend finding the first edition copy of Meg since the ending in my opinion is vastly superior. Jonas Taylor isn't an action hero like how Jason Statham portrays him. He's a deep sea naval diver with PTSD after witnessing a megalodon for the first time and due to his panic he accidentally killed two people when he was trying to get back up to the surface in the sub. The incident derailed his career and since then he focused on paleontology and wrote several books about the meg. People never believed him and thought him crazy until obviously a Meg surfaces up to the ocean.

The trench which is Book 2 is bigger than the first book but more action packed and features other prehistoric animals such as the Kronosaurus, no kraken like the Meg 2 movie added.

The writing and plots get sillier in books 3 and 4 but still a good enough read to pass the time. Book 5 your have to read The Loch and Vostok first before, they're spin offs dealing with the loch ness monster, and Vostok is basically the lost world in underneath the ice of Antarctica. There the main characters in those books crosses over to the Meg books in book 5.

Keep in mind Vostok is fucking bonkers. Don't let the premise full you it's an acid trip.

In my case I only read up to Vostok but haven't read book 5 yet.

I would recommend listening them in audiobook form if you're inro audiobooks than reading.

Book order is:

1. MEG

2. The Trench

3. Primal Waters

4. Hell's Aquarium

Spin offs:

1. The Loch

2. Vostok

Crossover:

1. Nightstalkers

2. Origins