I have one. It's fairly expensive and not a set it and forget it type device.
The instructions say you need to eliminate all breeding opportunities for this thing to effectively end the cycle.
I've done just about no elimination, but I do see a difference in the amount of mosquitoes. Unfortunately, they are worse now than they have been in weeks, but still noticeably less than in summers before.
I don't necessarily recommend it, unless you're going to put in the work to help it do its job.