Guitar pro will import Powertab, TablEdit, MusicXML, Midi, and ASCII. The last is the important one as it will import any text file of tab, provided you want to spend some time fixing its time signature, etc... afterwards. The import functions are invaluable since they enable you to use sources from just about anywhere.
However, if you look at tab on paper, you can guess, provided you know the song, that the baseline (or melody) has longer or shorter notes on the same beat than the opposite. When you open / import into GP, it will never distinguish them and they will always have the same length on the same beat (unless you completely choose to ignore the sheet notation, which was why I bought it to start). If you are trying to learn a song and you don't know that the baseline is half notes while the melody is in quarters, you will end up with some pretty awful sounding results when compared to the actual piece of music.
As an example: a practice from me from
four months ago that I learned from tabs. Listen carefully to the baseline. Now, listen to
Peo Kindgren play it. Ignoring the great gap in skills and tempo, and listening to the baseline, you can hear where tab can fail, and where GP fails because it creates improper sheet to go with the tab. This isn't really the fault of GP though, there isn't enough information embedded into tab for it to be able to tell for sure if it should be two half notes, or two quarter notes.
If there is a way to untie those, and set the proper lengths of those notes, I would love to know how to do it. I've gone through the docs, tried every feature that looked plausible in every menu and navbar, and still haven't figured out a way to do it.
I do agree it is great for practicing (when you are familiar with the material), song looping, backing tracks, etc.. They are all great features, but accuracy is really lacking. If you are looking to do new material, you really need to have heard it a few times and listen carefully to avoid making the same kind of mistakes. Watch out for the tabs you can find on sites as well. There is a reason that there are 7 different versions of that song, none of them are the same, and only one will be even close to being correct. I've seen tabs with the wrong time signature, wrong placement on the fretboard (sound the same notes, but different tone), missing notes, etc... and it took me about a month to re learn how to play some songs once I started taking lessons. I had to change fingerings quite often so that I could do better transitions while extending note lengths.
I guess what I am getting at is it can be a good teaching tool, but don't let it be your only tool to start, or you could fall into the same traps I did.