Pacy action thriller spoilt by ending

I've just finished reading Chasing the Dark by Sam Hepburn.

This book has a lot going for it.

The protagonist is a likeable, funny, brave boy called Joe on a quest to solve the mystery of his mother's tragic death. The support cast include a loveable but smelly Ukrainian ex-convict, Joe's geeky but clever best friend Bailey and his gangsta elder brother, a young Ukrainian refugee girl, a nice university professor, Joe's horrible aunt and some evil thuggish villains.

There is humour, mystery, action and pace - the pages kept turning as the pace was stepped up and mystery deepened.

The threads of the complex mystery are successfully drawn together in the exciting climax.

So why didn't I give it more than 3 stars? I wanted to. Halfway through, I thought it was on track for 5 stars. But the ending just went on and on and became totally cheesy by the end. Don't get me wrong - I like happy endings. I like it when things are resolved. But this was just too much...