Like the other reviewers, I didn't want to drill holes in my cupboards so opted for these. They have given 3 years of great service and I'd recommend them as a great product in the right situation. I'll summarize the pros and cons
+ well made, quality product
+ don't have to drill cupboards
+ in use they definitely stop the child and are easy for an adult to open, so they really work well
+ can resist intense tugging and jerking from a three year old
- need flat (non textured surfaces) to stick the locks to as may come off otherwise. I used neat alcohol to clean my doors before sticking on the clip and it's been rock solid
- quite difficult to line up so can stick in the wrong place and then can't reposition easily unlike screwed items - I mocked up the positions with Blu-tac first
- despite giving you various bits to support 4 distinct types of door closing set-up I still needed to make something myself so that they locked properly with some of my doors
So, as you can see, if you have suitable cupboards and you take the time to install them then they can be great but may not be for everyone. I have seen a lot of these where they've fallen off or simply don't lock because they've been installed out of line. As long as you appreciate it's not just a case of peeling off the back of the sticker and slapping them on then this product can be brilliant. After three years use it's hard to imagine a better product for my situation and there'll be no holes when I pull them off.