Pros: Very, very easy to install correctly.
Work very well.
Cons: Key could get lost.
We had a new house built and were looking for a way to lock the brand new kitchen cabinets without drilling any holes. These Kidco Adhesive Mount Magnet Locks are just the greatest! I was worried about mounting them, for fear of putting them in the wrong place and then the adhesive not sticking well enough the second time. But their instructions and the method of mounting them are so good, it was hard to do it wrong. It's probably important to follow their directions of not using the locks for 24 hours after installation, to let the adhesive patch set (which we did).
We chose to just mount them on one set of cabinets, and keep all dangerous things in there or in upper cabinets. We keep the key sitting on the counter top above this cabinet (rather than mount their included key holder) and have found this system to be very easy to use. It is important that you place the magnet directly over where the latch has been installed, but as long as you do that, the latch unlocks (i.e. the magnet pulls the hook down) very easily.
One thing I like about them, compared with traditional cabinet locks, is that when activated/locked, the cabinet cannot be opened even a crack. In our old rented house with ugly painted plywood kitchen cabinets, we didn't mind drilling into them, so we installed the traditional type of lock that requires you to open the door a bit, and then disengage the hook that holds the cabinet closed. This allowed our daughter just enough room to put her arm inside the cupboards, so we still had to be careful what we stored close to the front of the cupboard. These magnetic locks only allow 1-2 mm of movement of the door when it is locked.
There is also a switch on each latch that allows you to set them in 'unlocked' mode for whatever reason (and this is what you use while the adhesive is setting).
We have had these installed for 3 months now, with no problems whatsoever.
The person in the store (who has them in her home) warned me that if you lose the key, the magnets that might be found in some kids toys will not be strong enough to open the latches (which is probably a good safety feature!). So be sure you either buy an extra key or just don't lose the one you have!