It looks like 2013 was a very successful year for Windows Phones, even though Microsoft's smartphones may seem like a major underdog in the current mobile phone market - taking into consideration the massive competition from Apple and Samsung. Interestingly, recent analytics show that Windows Phone devices have actually outsold the Apple iPhone in 27 countries, and sales have jumped by 156% over the last year.
Microsoft's strategy of targeting Eastern and Central European markets is definitely paying off, because the majority of Windows Phone users are located in countries such as Poland, Ukraine, Russia, Italy, Greece and France. Surprisingly, the Windows Phone OS itself is not the reason why Microsoft is doing so well in Eastern Europe. 93% of Windows Phones are made by Nokia, which has been considered the strongest and most trustworthy brand, having the highest sales rates, and is still one of the most popular mobile phone manufacturers in most European countries. People rely on the well-known hardware brand, rather than technologically advanced software.
Being from Poland myself, I think the strong reputation of Nokia is not particularly reflective of the brand. The main advantage of Windows Phones is the price (sometimes even 3 times cheaper than iOS or android devices!). The majority of WP users are young people aged between 16-24, mostly students or young working professionals. What's more, wages in Eastern Europe are much lower in comparison to Western Europe or America, therefore people simply cannot afford expensive smartphones, and choose the balance of price and functionality. The Poles are one of the biggest enthusiasts of Windows Phones (with the highest market share in the world - 16.3%). Poland also has one of the highest number of WP developers, because the competition on the Microsoft apps market is relatively small.
To summarize, the Windows Phone has achieved large success and growth in many developing countries due to its reasonable price and functional open-source software. Although it is a cheaper equivalent of other popular smartphones, it is no less practical.