I wish I had read the 1-star review before purchasing, because exactly the same thing has happened to me: after just six months of use the key snapped! I had used the lock often, but not even daily. I SWEAR I didn't use any excessive force (I wish I could say I had underestimated my own strength, but no)!! Luckily I was able to insert my broken key on top of the snapped off piece and carefully unlock it, so my boyfriend and I (I had chained his bike up as well!) could cycle home and I didn't have to go through the pain of getting a grinder or a locksmith on the scene. I wasn't able to pick out the snapped off bit, so after just a couple of months of use I could bin the lock. A real shame, because up until then I was very pleased with it.
The key is definitely the lock's "weakest link" and since ABUS will pass it off as a user error, and will therefore take no responsibility what so ever, I would NOT recommend this lock!!