I've started maining TF more and more thanks to your thread and the visual rework that Riot had given him. To be honest, he's quite powerful, what with the ability to zone and control your opponent's movement in lane with Q, strong assassin/roaming tool with his ult (you could burst down a squishy from full whereas with Karthus you depend on your allies getting them low enough to ult), and, the most important and fun aspect of him, his pushing power. Red Card into Q clears a minion wave before the minions allow enemy vision of you, and you burst down a tower with your attack speed + blue card before they have a chance to react or send someone to distract you. Sure it might be a 4v5 for your team, but they're barely touching your inner turret and you're already knocking down their inhib. By the time they get to you, you can ult into another lane and push from there, not to mention predict your enemies' movement with it. It's better than a few wards to be honest.
He's also the first and only male fanservice character in League of Legends.
So no, he doesn't need a buff at all.