Overview
When the Windows 7 smartphone burst into the commercial scene, consumers were intrigued by the whole new Metro interface, touch attributes and the OS integration with other Microsoft services and third parties. And, now we are to witness the much heralded update to this operating system platform in the form of Mango. But hold on to your horses, the upgrade is actually about a month away. That does not necessarily mean that we cannot nitpick about the features presented by the early beta releases of this touted major update.

Price and availabilityAccording to Microsoft's Windows Phone Vice President Joe Belfiore, the Windows 7.5 devices should be broadly available from October 2011 globally, with the first launching congregations in Europe and Asia. Information based on the details of pricing will be available after that.
What’s great?
According to sources Mango (aka Windows 7.5) adds around a whopping 500 upgrades. Some of the crucial ones are related to improved multi-tasking capability, controlling features for 'People Hub', integration of Internet Explorer 9 and newer access ability to Twitter and LinkedIn.
The special attribute of Mango in simple words is its long-awaited multitasking capability. This facet allows the user to seamlessly move between a plethora of apps and work/resume with them. Complimented by a wireless 4G connectivity, this accentuation is surely a winner in our books. Though, it should be duly noted that some people may find the feature a tad bit unorthodox, especially as it is not in-sync with the other features of the phone
Coming to People Hub, sometimes it can get tedious with a slew of 'societal' info and contacts traveling your way and holding your attention. Well, with new features like the Group, you can actually control this copious magnitude of overlapping information. This attribute allows you to select a group of people whom you can give access (and thus filter the overall content). Another related feature Threads allows you to glide between text, Windows Live Messenger and Facebook chat within the same scope of interaction.
Any smartphone user would know the importance of the integrated web browser with the device. Taking this aspect into consideration, Microsoft has decided to include the latest version of Internet Explorer 9 with hardware acceleration support. In a testing phase by Pocket-Lint, the phone's hardware quality came second in performance after iPhone (with iOS 5).
Finally, for the more socially inclined among us, Mango will integrate Twitter feeds without the requirement of any separate app. LinkedIn has also being promised along with more improved features for the already included Facebook.
What's not so great?
In simple words, Bing with its supposedly poorer search capacity. For a legion of users used to Google (along with its maps), this search engine may come as a bit stiff for the beginners. Bing does have a few tricks up its sleeve like the Bing Music, Vision and Voice attributes.
Also, at least up till the beta releases, Microsoft has not included any 'Cloud' back-up criteria. This means that if you are making that transition to a different Windows 7 phone, those self created tiles, Groups and downloaded apps may not be saved.
Things to watch out for
The biggest thing is obviously the much improved iteration of Internet Explorer 9 with its performance capacity being notched up. The page exhibits that convenient uncluttered look with the address bar at the bottom. Moreover, now you have the option of sharing web pages through messaging, email or social networks (surprisingly this feature was not present in the earlier versions).
Coming to social networking, you can now have access to a more expansive photo sharing feature with Face Detection and People tagging. There will also be an auto-fixing option (similar to iOS 5) for an improved light ambiance for those darkish photos.
And finally, if you are an avid gamer, the all new Xbox 360 look with 3D avatars will certainly appeal to you.
Verdict
It is too early to comment upon the overall stature of this massive up-gradation for Window 7. But from the very first impressions, we have to say that for a change Microsoft has followed the path of total integration with conspicuous societal features like Facebook and Twitter access. And with the intrinsic vivacious look, users would surely feel a tad bit cheerful when working with this colorful OS. So, overall we have to say Mango does offer something transiently unique, but can still offer a fair battle to its more eminent peers like iOS and Android from perspective of sheer performance.
Other alternatives
1) Apple iOS 5: It will include the iCloud service and Notification Center. It will also incorporate a myriad of new apps along with improvements to the older ones.
2) Google Android (Ice Cream Sandwich): It will include a totally refined UI, an extended screen support API and an ability to directly load data from SD cards. Basically it will fuse the previous versions of Gingerbread and Honeycomb.
Further readings or word around the web
If we've sounded gushing, that’s because we are. Windows Phone 7 is a mobile operating system that offers something very different to Android and Apple's iOS, while still giving them a good run for their money.ZDNet:
Over the years, I have tried different 3rd party applications and integrated services to try to control my iOS, Android, Symbian and BlackBerry devices just with my voice. Some apps and services did well, but NOTHING has functioned as well as Windows Phone 7.5 (aka Mango) from Microsoft.