It's not just HTC, it's all Android phones. So with iPhone you get:
Apple issues the new firmware -> you get it. Job done
whereas with Android you have:
Google issues the new firmware -> the manufacturers (HTC, Moto, SE, etc) fiddle with it -> the teleco's (Orange, Three, Voda, etc) fiddle with it -> (finally) you get it.
Which means that Apple can get firmware updates out there for iOS far quicker than Google can for Android.
The Android way is old-style phone-stylee and imho just plain stupid (e.g. why the heck do the teleco's have to get involved with updates - aren't they just merging with existing system files?). Apple's way is just superior in about every way (apart from having to use iTunes ) and something I'm envious of.
Of course, you can always root your 'droid phone (which is reputedly easier than iOS) and then apply the new firmware manually, but that's cheating and too scary for me.
Bob