I got one of these to trial and like it so much I now have 1 for each of my 3 fish tanks. The cable is just about the right length to have the sensor near the bottom of the tank and the display near the bottom of the glass. The suckers work quite well and I've tried all 3 in water with an existing thermometer, and all came out within 0.1 c of each other.
The only thing I could think of to improve them, would be to make the viewing angle a bit better as I find I've got to be almost at eye level to read the display. Other than that this is a great product - especially for the price!