Good if it works, don't impulse buy! Check reviews and measurements first...
Good product if it fits. Measure the space under the window sill, you need up to 10cm clearance (between window sill and radiator) and at least 5 cm of window sill sticking out. I bought this for specific window, but ended up checking all the others just to find one I could attach it to... Still didn't get a great fit... The screws are visible as well, so not great if placed opposite furniture such as bed/sofa (when it's in your eye level or above). It spoils the look.
BUT, My cat loves it!