The reason this works so well in mid- late is because of the critical chance that you will have with the attack speed you have and the passive. Overall these alone are reasons why AD is better for jungle twisted fate. Along with those though since you will have 2.5 attack speed and 75% critical dealing 250% of that and 261 dmg at the end of it you would be dealing dealing 750 damage(if you go ruined king). The amount of power you can have late game is astonishing, but you must have the support of your team. His early ganks are not gonna do much damage but are necessary to get going, so your team will need to help on your ganks by dealing damage and not just sitting around. Now beware of his slow start but once you get to mid-late game you really can kill people, you should be able to 1v1 3-4 of the enemies on the other team. Maybe 5 if one lane does not feed.

With this twisted fate his ganks are very important. When your level 6+ you will have the ability to get that last hit on the one that got away from your allies in the lanes very easily. Along with the fact that this can be used to engage in ganks. I recommend activating ult, then pick-a-card and then quickly teleporting with your ult to the lane behind the enemy. Although hard to master the gank for some people because of time restraints and team communication errors. When done correctly it can be deadly. It can change the whole flow of a lane.
Another good method is to ult into a bush so they will never know. But this time you wait. this is for wanting the enemy to push up first or waiting for a teammate. The reason you want this is because the eye will not appear above the enemy head when you gank so they will not expect it. It also deletes all time restraints that the other method had. Both of these methods work very well and have great payoff.