Pro: You can move your pet while still being in control of your character.
Con: Your pet doesn't "jump" ledges.
I discovered the latter point yesterday and wiped my heroic 5man group with it; luckily it was a guild run and not a PuG.
Sadly, this means we'll have to dismiss pets before jumping down in dungeons... I know it's only a 2sec cast time and your pet doesn't lose happiness anymore, but I still don't like doing it - waving goodbye to a pet never seems nice :(