Best way to see is to try the trial of the paid app, then try the free one and see what you miss. One thing I know that's not in the free version is the temperature icon in the notification area.
I tried getting the trial, but I kept getting an error message and then it said my trial was over. Actually I'm using the free vs now and it shows the temp w/ the icon.
If you go to the website it tells you all the advantages.
But here's a few, your icons look amazing in the paid version, they're kind of cartoony in the free one.
You can track 10 locations vs. 3 in the free.
There's a temperature badge that goes in your notification area not just on the icon.
There's also a local advisory option that warns you of things like freezing rain/hail/high winds etc.
You can set it to be your background, which looks beautiful, and comes in handy for themes that don't have a weather slot.
It has radar maps so you can track a developing storms in your area
And yeah, I think there's some more. Check out the website for pictures and what not.
I used the free version until it went on sale for $5 instead of the full price $10 and I suggest you do the same if you like it enough.
Posted from my CrackBerry at wapforums.crackberry.com
