Windows Phone has been heavily locked down by Microsoft so unlike on Android phones, you don't see much variation from phone to phone. Once you're familiar with one Windows Phone, you basically know the rest. The only things different manufacturers can tweak are the included apps, and Nokia has indeed added some quite compelling ones which we'll come to shortly. But first, the basics.
The key component to the Windows Phone interface is the Live Tile. These large, rectangular icons not only act as links to your apps (webpages, contacts and many other things) but can also display information such as new messages, status updates or photos. One particularly good example is the Nokia App Highlights tile that periodically promotes new or favoured apps, prompting you to take a look in a way that's useful rather than annoying.
The Live Tile idea is a good one and works rather well. The only downside is that the Live Tiles are arranged in one long list that can get rather long and unwieldy once you've crammed it full. Swipe to the left or tap the arrow in the top right corner and you've got the full list of apps available on the phone.
One thing to note about the Windows Phone interface is that you're very limited in how you can customise it. You can choose for the background to be white or black and select one of a small range of colours for the Live Tiles. However, you can't add a background picture, which is an easy customisation many people like to make to their phones. Likewise many basics settings are very limited, such as the manual brightness control – rather than a slider you can only choose from Low, Medium and High.
The other key component to Windows Phone is how integrated everything is. Login to your Windows Live, Email, Facebook, Yahoo!, LinkedIn and Twitter accounts and you'll find the photos app populated by your albums from Facebook, your contacts from all these services integrated into the one 'People' hub and your Calendar fully crammed. To a degree it's something many other phones offer (particularly Android ones) but on Windows Phone it's so consistently done and tightly integrated that it feels really natural and a real boon.
A good example of this is the Search function. There's a dedicated button for search and when tapped this brings up the option not only to search your phone for contacts, emails and such like - as well as perform a web (Bing) search - but also has three further options; Music, Image and Voice. Tap Music and the phone will listen to the world around you and identify what music is playing. Yes, it's just like the widely available Shazam app but it's great to have it integrated. Image will bring up the camera app and then use it to perform real time translation on any writing within the image, or you can copy the text and paste it into an email or a Word document, or you can scan a QR code. Again, it's not a unique ability but it's great that it's so easy to use. Finally, there's the voice option which simply invokes the voice recognition software, allowing you to speak you search.
Coming onto those Nokia apps, there are just two but they are very useful. First up is Nokia Drive which is a completely free sat nav app, which includes maps for the vast majority of the world. The maps are large and do need to be downloaded in advance but once on the phone you don't need any data connection on your phone to use them. So if you're abroad and want to find your way around but don't want to incur the high data costs of using something like BingMaps then it's a real boon. The interface isn't quite as good as some dedicated sat nav apps such as TomTom for iPhone and ALK CoPilot Live Premium but for a completely free solution it's more than adequate. It's worth noting, though, that you don't Nokia Maps, which is a similar service but one that presents the maps in a style more akin to GoogleMaps. For that style of mapping you'll have to rely on Bing Maps.
Nokia Music, as well as giving you access to the music you've already loaded on the phone, adds a well stocked mp3 store, a local gigs finder and its standout feature, Mix Radio. This presents hour long playlists of music that you can stream or download for free and listen to as many times as you like. You can keep up to four on your phone at any one time and the selection of playlists while not vast is good enough that most tastes are catered for. Considering it's free, it's a real boon.
As for adding other apps, the Windows Phone MarketPlace is still understocked compared to Android and iOS (10s of thousands rather than hundreds of thousands) but we did find a reasonable selection of our favourites. Spotify, Dropbox (unofficial) and Runkeeper were all catered for as was Angry Birds and Plants vs Zombies but Stumbleupon and Cover Orange were two examples that weren't available. The MarketPlace is growing but perhaps not quite as fast as one would hope.
Web browsing is in general quite good with an easy interface, fast operation, correctly rendered webpages and an easy zoom system. However, the lack of Flash puts it a step behind Android phones.