Tablet PCs... are they worth it yet?

I'm going back to school in August. I have access to one (or two) laptops I could use, but I'm considering getting a laptop for myself.

I was looking at the Tablet PCs today at J&R. I especially liked the Portege 3505 because it has a pretty big keyboard and it's still fairly lightweight.

For those of you who have one (Marcie?), what have your experiences been? Do you think it's worth it? Can you do development on it? Do you find yourself using it as a laptop or a tablet more? How good is the handwriting recognition?

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