I'm not to too familiar with Guitar Pro either, but after a quick look at their website, it seems like it's geared more towards music composition than it is viewing song tabs. That being the case, it seems like the software would really be overkill if you're essentially just going to be using it as a tab viewer. I suppose functions like playback, tempo control, etc might be useful, but that would only utilize a small portion of what you'd be purchasing.
I have used the free Tab Pro tabs over at ultimate-guitar.com periodically. That can be pretty useful, but I've only ever used the free version. I don't know if those tabs are any more reliable that the text based tabs that are available from ultimate-guitar.com. Actually, I've found that the poor text tabs (as long as they're not too far off) at ultimate-guitar.com or other sites can sometimes be helpful. As I'm learning, I can identify problematical portions and correct them (to my ear at least). I'll also sometimes combine various sections from multiple tabs into something that I feel is more correct. It's probably a safe bet to take all these tabs with a grain of salt though, unless you're going to actually purchase real tab books. ...And I have no idea where you would purchase Guitar Pro tabs, what the selection is, and how reliable they would be. I didn't see that info on their website.
Lastly, I'm only a novice at best, but I've always found that if you have a tab (good or bad) it's easiest to simply listen to the actual song you're trying to learn. Now a days, I just use grooveshark.com (if a song is available there). That way you can play a specific song on demand, pause, rewind, loop, etc as much as you want. It's not a perfect solution either but it's workable.