This bike lock will keep your bike safe! They even put a guantee on it; so if someone comes along and breaks it open, Kryptonite will replace your bike for you!
My only problem with the lock is the weight; I knew it would be heavy (I even went into Evans to have a look at it before buying for the much better price here on Amazon) but it is almost too heavy; I have to leave it at work as it is uncomfortable to carry in my bag and I don't want to scratch my bike by looping it round part of there. However, this is my opinion, and as I have experienced back troubles in the past few years it may not be something you experience.
My only other problem, is that as I left it at work, in both sun and rain, the internal mechanism has got a bit rusty, and sometimes it takes a good whack to open the lock; which I am scared one day will get me in trouble as someone might think I am stealing the bike!! This is despite the weather cover, so therefore I am going to give it 4 stars.
Overall very happy with the lock! Well worth the money!