Let's compare the Lumia 900 to four other smartphones: Apple's iPhone 4S, HTC's Titan 2 and One X, and Samsung's Galaxy Nexus.
The Lumia 900 is one of the thicker phones in the bunch, at 11.5mm thick. The fattest phone is actually another Windows Phone device: HTC's Titan 2, which measures 13mm thick. The sleekest phone is HTC's One X, which is just 8.9mm thick and weighs 130 grams.
The Windows Phones in this comparison suffer from slower processor speeds and lack of memory. Both the Lumia 900 and the Titan 2 have single-core processors and 512MB of memory, as does the iPhone 4S. The other phones (the One X and Galaxy Nexus) feature dual-core processors and 1GB of memory. The HTC One X will have a quad-core processor overseas, but this version .
Dual-core chips and 1GB of RAM are commonplace in today's smartphones, so I can only assume Nokia decided to go with a single-core processor in order to cut costs for the customer.
The Windows Phones also lack in storage--the Lumia 900 and the Titan 2 only come in 16GB versions, while the iPhone 4S has multiple options (16GB, 32GB, and 64GB), and the Galaxy Nexus has 32GB of space. The U.S. One X has only 16GB of storage, but the overseas version has 32GB. None of the devices compared have expandable storage options.