I always used an 8300 then upgraded to the 8310. Thought it was the best thing in the world. One day, I decided to sell my 8300 since I now had an 8310. With the money from that sale, I purchased an 8820 from at&t premier for $149...to make a long story short, that was the day I packed up my 8310 and placed it in my closet.
The 8820 is such a sleek looking phone. It is more business-centric which is something so important to me while in the office. It has a great keyboard, feels like a rock, does not squeak on the sides, has a fantastic build quality, does not suffer from this "dust under the screen" nonsense, it is just overall a fantastic device and quite frankly the best BB I've ever owned.
Coming from someone who is a huuge Curve fan, the 8820 is by far a better choice, IMO.