Overall, this is a good simple design for the job. Avoid any products designed to kill them as you may end up with a poisoned or maimed rat in a wall space where he cannot be removed.
I think some users may have had problems only because this is a mass produced item eg sticky doors, stiff trigger bait plate, etc... can usually be fixed with some patience.
I made 2 useful modifications:
1. where the 2 trigger rods meet, bend the top door rod (at approx 10mm from the end) slightly to the left - instead of leaving it vertical . This makes it easier to set and not so sensitive.
2. place 2 bricks on top of the cage to avoid triggering in case the rat brushes against the cage
When you get him, let him go into a field where he can make a tasty meal for an owl.