Apple only have two current handsets and a few older ones, so less than ten in total that will get updates. Apple also separates carrier customisations from the firmware so that they're able to only test their updates on those handsets that the new OS will live on even then, they still get their day one problems they have to fix).
With Windows Phone, there's a different hardware for each variation of handset/carrier/region. This means that there's no separate configuration files that can adversely affect your phone (or do something illegal for your region). For Lumia phones, there's over 2,000 versions of the firmware to test and deploy. It takes time to do that.
Hopefully, you won't have to wait too much longer for yours to come through.