All I can say is prepared to be disappointed from coming from the iphone re the music player. The music player on N900 is a big. m-e-h. Also, I don't believe the N900 has hardware decoding of MP3 so you won't see same battery life you would with iPhone or iTouch in that arena.

There are some other quirks with ID3 tag sorting and playlists which you will have to get used to.

That said, otherwise, the N900 is a really good phone, and it has your first 3 points covered, easily.

From my own experience with the N900 in NYC, compared to the iphone, the GPS blows big chunks, it is slow to aquire a signal - upwards of 5 minutes, which is just a joke.

Just be aware that while I really like the N900, it is missing the polish you have grown accustomed to while using the iphone.