The interface of Windows Mobile 6.0 was sluggish and so poor that many handset manufacturers such as HTC and Toshiba have overlaid it with their own bespoke software - changing the cosmetic appearance of the OS for the better.
Announced in February, 6.5 has been a long while in gestation. In fact, infuriatingly long. It seems strange since all the signs point to the announcement of an all-new Windows Mobile – version 7 – at Mobile World Congress in February, only a few months hence.
When 6.5 was announced we had expected it to debut in the summer, but Microsoft decided to wait. The rebranding as Windows Phone is because Microsoft believes most people don't know what OS their handset uses, but would plump for a Windows-powered device because it's a name they know.
In Europe, operators Orange, Deutsche Telekom and Vodafone plus phone manufacturers Acer, HTC, LG, Samsung, Sony Ericsson and Toshiba will have Windows Phones at launch.
So what is Windows Mobile 6.5 like to use? Initially, the interface feels a lot slicker than before. The honeycomb home screen is nicer, while (and this depends a lot on the hardware obviously) it was more iPhone-like to flick up and down the apps you have available.
The icons themselves also look far better and Microsoft has really tried with the look and feel – and it's worked - here's Windows Media Player, for example.
Indeed, the improved interface echoes the Zune menu system – no surprise as both Zune and Windows Phone inhabit the same business unit at Microsoft.
However, the new parts of the interface remain paper over cracks – the old-style Windows Mobile dialog boxes and interface is still present behind everything, it's just buried a bit deeper than before.
The lock screen has been improved a great deal, with notifications of missed calls, answer phone messages and new texts as well as direct access to these services with an unlock-swipe of the finger.
A completely overhauled and now Zune-esque Today screen shows any currently active item as you scroll through. Here there's a song playing, but you can also see things like the number of emails in your inbox.