I bought this as a disc lock, but when I first tried to fit it to my bike I struggled to get it through the holes on my brake disc. I put that down to fact that I don't have a mainstream bike (Cagiva Raptor).
In the end I found it easier to put it through a fork on the wheel, although I always had to collect my thoughts and steady myself before doing so, because it would nearly always go off before I completed the task. My speed inproved with time, but I had to give up closing the cover on the key hole because I simply had no chance.
I read reviews before buying it saying about the fact it went off in heavy rain, but I brushed that issue under the carpet as I though that would be rare. I can confirm that it does happen in a mild downpour. Saying that, the alarm was so quiet I only just heard it, but I thought I should go out and disable it (in the rain - by swapping round the way you put the U into the body) just in case my neighbours got upset.
In the end I decided to revert back to my old, simple disc lock, but I also fixed the Oxford one to the frame under the petrol tank, where it was protected from the rain whilst on the side stand. I thought at least then I would have some form of alarm, and the fact that it's flourescent yellow makes it a visible deterent.
Alas it was not meant to be. Someone then knocked my bike over, with the Oxford taking a huge hit, so now it's purely a visible deterent that lets out a dying chirp or two now and again. Would I buy another one to replace it? Probably not.