It is not about the size of the megapixel, it is the size of the lens that count. The bigger lens will have a better sensitive sensor to light. Where light is the source of image. No light there will be no Image. The more light goes in, the better colour and picture though on the same megapixel rating.

My N93i is better taking picture close up than my N95. Because of the Optical Zoom.

On the other hand. N900 was designed to take professional picture anyway. None of the professional photographer use the N900 to take pictures. N900 is an Internet Tablet + Phone. lol nothing about Camera factor.