Now take a look at Android handsets. Not Android but the manufacturers that use it. They all have varying support for the latest version of Android with some shipping older versions months after a newer one has been released and many simply not offering updates. I fully admit this isn't up-to-date but here's what I read some time ago (link).
Most manufacturers are sucky in some shape or form, personally I find Apple pretty decent and from my direct experiences better than Nokia and LG.