Personally I think the n900 web browser is better than the iPhone & android-based phones. It feels more like a "desktop" experience than the others.
The strength of the browser means I do not need to download dedicated apps for Facebook & Google.

I never have issues with 3G and wifi. I take it for granted the n900 has a reliable connection.

Flash sucks on the n900. It has not been optimised for graphics system and as a result Flash is slow. Videos can be a bit choppy.

Despite it's size the keyboard is very useful and easy to type on.

I play many emulated games on the n900 (GBA, SNES, C64).

Many of the applications available can be a bit geeky for some people. But there are still many useful apps available.

The iPhone & android are entertainment devices. The N900 is more practical.