Best things so far about my Desire:

An app called handtec - its is sooo configurable. Like the N900 SMS Customization thread where you have to go in a code everything and play with font sizes. This app does it all with parameters in a nicely laid out menu structure. Something the N900 isnt very good at!

Also the street view google maps navigation is just awesome and works a treat.

I have no regrets about buying the Desire.