This worked fine at first- yes, the tunes are mostly cheesy, but it's nine quid!
However, it stopped working quite quickly. I found that it seemed to lose sync between the bell push and the main unit, which meant pushing the button again and laboriously cycling through the tunes to one of the few non-cheesy ones.
But worse - even when sync'd, it didn't always work. If I took the bell push off the frame and brought it inside, it's fine (but useless, of course). Just being fitted in place seems to hamper the operation. Note that it's a good old- fashioned wooden door frame where it's fitted, and should present no barrier.
Gone back for a refund, and I'll buy something else.