I've been thinking about getting something like this. I thought that a remote laser temperature reader was going to be the answer to my prayers, but plywood tanks and/or thick glass give you a skewed reading, as the laser is measuring the temperature of the outer surface and that can be several degrees different than the contents. The laser works great for the big plastic bins I store water in (thin walls, no discrepancy), and for measuring aquarium temperature by shining the laser at the water surface directly.
The probe would require opening up the lid to insert it; but once the lid is open, I might just as well use the laser on the water. Plus, the laser pointer type is a cool little toy that helps out with such things as locating heat leaks in walls, etc.
The cheap little electronic versions of this that can be stuck to the outside of each tank, with a probe installed more-or-less permanently in the water, are still my favourite for most aquariums.