Windows 8 apps are a welcome change from iOS. Among the three ecosystems, I prefer Android, Windows 8, and iOS in that order. Blackberry, what ?! For ease of use, Windows phone is really easy to use. Lumia 900 has been succeeded by Nokia Lumia 920.  For someone interested in a first smartphone which doesn''t break the purse, Lumia 900 is an excellent choice. User interface in Windows 8 is very pleasing and this is one of best phones with awesome user experience. If you prefer great user experience over infinite hackability, aka Android, then Windows 8 phones are great choice.Lumia 900 has 4.3" (109 mm) 800x480 resolution 217 ppi 16m compared to the Lumia 920 which has a 4.5" IPS LCD, 1280x768 resolution, 332 ppi display. This phone has up to 16 GB storage and 512 MB RAM compared to Lumia 920 which has 32 GB storage and 1 GB RAM.  Lumia 900 has 8 MP camera and 720 p video compared to Lumia 920 which has a 8.7 MP camera and a 1080p HD Video.  1.4 GHz Qualcomm Scorpion processor compared to Lumia 920 which has a 1.5 GHz dual core processor. I have extensively used in the past HTC Titan I and II which is pre Windows 8 (7.5) and I was surprised it has become more buttery smooth now. This phone has Gorilla Glass  compared to Lumia 920 which has Gorilla Glass 2. Glass 3 is in the making and supposed to be even better. Stating following because this is highly underrated in reviews. From Corning''s Gorilla Glass specs; WHAT MAKES GORILLA GLASS SO DAMAGE RESISTANT? The unique composition of Gorilla Glass allows for a deep layer of high compressive stress (created through an ion-exchange process). This compression acts as a sort of "armor," making the glass exceptionally tough and damage resistant. Ion exchange is a chemical strengthening process where large ions are "stuffed" into the glass surface, creating a state of compression. Gorilla Glass is specially designed to maximize this behavior.As you can see Lumia 920 has, what I would say incremental upgrades over 900 but nothing earth shattering. Lumia 900  as well as 920 does not support microSD expansion. I always feel this is a bummer. But with 32GB it is plenty with current app ecosystem.  These phones seem to be copying iPhone philosophy.  Battery 1830 mAh Lithium polymer battery (Compared to a high end Android Galaxy Note II, which has a battery of 3100 mAh Battery.) Unlike the Nokia Lumia 820, the Lumia 900 as well as 920 doesn''t have a removable battery cover, which means you can''t access or replace your battery. __Not having a storage expansion slot is a bummer for lot of people! Not being able to remove battery is a double bummer.__  For me, storage expansion and removal of battery is very important, so I was disappointed. This is the downside the unibody design.Phone quality was excellent and speakerphone was awesome. Nice to see built in active noise cancellation with a dedicated mic.  Lumia 900 has Bluetooth 2.1, whereas  Lumia 920 has Bluetooth 4.0. I was able to get excellent reception with Bluetooth headset, Jaybird Sportsband Stereo Bluetooth Headphone - Bulk Packaging - Midnight Black and JayBird BlueBuds X Sport Bluetooth Headphones - Midnight Black  All the usual smartphone stuff, facebook, twitter, music, emails etc are all excellent. It is only the third party apps that are lacking in some arenas. If you are Microsoft heavy like Office suites, Lumia phone are awesome!Lumia 900 has the diagnostic tool. It can be obtained by pressing ##634# on the dial keypad, which should initiate the download after the last # is pressed. The diagnostic tool should appear on the app list under Diagnostics.On this diagnostic tool one can run tests on the following: Accelerometer, ALS, audio loopback, camera, battery status, DTMF, gyroscope, hardware buttons, headset detection, LCD white, lights, life timer, magnetometer, power source, proximity, speaker, touch and vibration. It''s also possible to perform all the tests in one run. This is really cool to have this power at the user''s hand!Apps are limited in Windows 8 marketplace. Yes, we have heard this a gazillion times. Lumia has GPS receiver with A-GPS and GLONASS support. I tried with Garmin Navigon app which turned out to be great in giving voice directions. App ecosystem is a chicken and egg situation. Unless more phones are sold, developers don''t have incentives to write apps. Apps are less now, because people are not buying in big droves. Windows Phone is now (early-mid 2013) the third-leading mobile phone platform, more than tripling its market share year-over-year. One recent report I read Android and iOS are ahead in games with 162.1 and 37.4 million shipments in 1Q13 and Windows phone came in 7 million. This is more than double from previous year. I really hope for Windows 8 platform to surge ahead because having a 3 way competition with iOS and Android is good for the ecosystem.ONE LINE SUMMARY: The Nokia Lumia 900 is certainly the best and cheapest Windows Phone 8 smartphone on the market, it was really the best in 2012, but if you don''t mind the budget get the 920 or 820 (for microSD card slot).