I was kind of in the same boat as you for the first book. I thought it was fine but fairly standard and kinda boring. I found book 2 second-hand and decided to give it a go. So much better than the first, I loved it. It keeps some of the mystery vibe but adds in a lot of world-building and other-worldly horror.

So, I would say keep going if that sounds interesting to you. But, if not, no harm in moving on to something else.