The only thing about PDA Net is the free version doesn't allow you to access https (secured) websites, and you have to pay (if I recall correctly, Robert can correct me if I am wrong) 29.99 or something per month to use it to access all websites (unless something has changed since it first came out).
Rooting your Droid Incredible and installing WiFi tether takes ten minutes, and you don't pay a dime more than your existing data plan.
[ame="http://www.youtube.com/watch?v=VVHj6J2uCKo"]YouTube - HTC Droid Incredible Root in 10mins[/ame]
That being said, you can't be a complete novice with computers or you will be completely lost in the first couple of minutes.
If you have a Moto Droid, however, the process is even 10x easier and doesn't require using the ADB shell program to work. The HTC DI will get to that point but they just achieved root a couple of weeks ago and still are streamlining the process.
Not to mention I'm going to guess that WiFi tether gets higher connection speeds. If I am in a full bar 3G area, my Moto Droid will max out around 32-35MBps download, usually hovering around 17-20MBps. I believe (and again I could be wrong) the highest BT transfer you can get is 24MBps, and of course you aren't going to see the max.
EDIT: I found a thread on the PDANet forums that say the expected transfer rate using the program is only between 300-600kbps. VERY slow.