Windows Phone 7.5 Mango is definitely an upgrade for the mobile operating system. The 500 new features don't make the system cluttered or confusing, despite adding improvements, fixes and new features in almost every area. Instead they fit in with the existing user experience and enhance it.
This means the operating system has the same elegant and engaging user interface as ever, with colourful tiles and plenty of white space – but it now also has key features that were previously missing to help it match the current versions of iOS and Android. Some aspects even leapfrog other platforms.
It runs on all existing Windows Phone 7 handsets too. While newer phones have updated Snapdragon 8x55 or 7x30 processors, original handsets such as the HTC HD7 didn't feel slow or sluggish at all under the updated operating system, even with many large web pages loaded.
In fact, older models felt faster and more responsive than when running the original Windows Phone 7, although fast task switching and background apps certainly help with that.
Even newer phones still have single- rather than dual-core processors to keep battery lives reasonable, but we didn't ever feel that the devices were slowed down for lack of an extra core.
In short, just having a better hardware spec doesn't make something a better phone. What Windows Phone 7.5 does is take really good advantage of the hardware you have.
Full HTML5 browsing with IE9 is an excellent new addition, as is the great Twitter integration, including sharing and groups to organise updates from friends.
Multitasking means you can switch between a few current apps quickly.
Voice recognition and handy new ways to search are finally available for UK users as well as US Windows Phone users.
Internet connection sharing is at the whim of the mobile phone operator, and only for new phones.
The otherwise excellent Twitter integration doesn't include direct messages.
Apps need to be written specifically to take full advantage of multitasking.
There's no Flash support (although YouTube videos play without a separate player, they're still full screen).
Some features – text to speech directions, indoor maps, traffic – are still US only. Others – hyperlinked addresses and email – work better for US addresses and numbers than for UK ones.
Windows Phone 7.5 is supremely usable, surprisingly powerful and delivers the experience Microsoft has been promising, with only a few rough edges left.