I don't think there will be a restocking fee if you've only had it for a few days. Just return it if you feel it's not the right phone for you. When I preordered my phone from Dell I asked a few of the customer reps if there was a restocking fee if I were to return it and they said no. This was during the Dell preorder fiasco where they were shipping out recent orders before they shipped out month old preorders, so I had also preordered one from Amazon, and wanted to make sure I could return the Dell one if they shipped at about the same time. Or you could could just call Dell to confirm it (and make sure to get the rep's name just in case).

As for me, the N900 is probably the best phone I've ever owned, and I usually switch phones every few months .