The play styles aren't very different. Vayne lacks a good escape and relies on good use of her e to create distance. (Using it defensively) Top lane Vayne is a bit more forgiving in he sense that most top laners are melees that will need to "go in" for their damage. she's definitely viable versus less bruiser oriented picks such as Nidalee and Nasus. Avoid picking her into tanks with hard CC or a hard engage. Malphite or Irelia are laners you want to avoid. Passive laners that rely on farming are good opponents.
As for mastering her, it takes some practice. Vayne is a really flexible carry that has opportunity to outplay but is still squishy and has one of the shorter attack ranges.
A few Pros and cons...
Pros:
Good damage vs tanks with W
Scales into later game along with tanks which means easier laning.
very mobile compared to most top laners. Q
Attack damage steroid for engages/ outplaying
Late game monster
Cons:
Squishy
Requires good mechanics and game knowledge to avoid being locked up.
Weak early - susceptible to ganks
No hard, reliable disengage.
Finally my verdict.
With good practice, Vayne top can be viable.