I'm been playing the absolute shit out of this game, and it's worth reiterating, this game is AMAZINGLY well done. Easily one of the best games of its type I've played in a long time.
The gunplay is solid, and the Titan/Mech handling is the best I've encountered since Mechwarrior.
One thing that really impresses me about this game is how well balanced things are. Certainly, there are weapons which are better than others... and certain weapons like the Devotion LMG feel cheesy. But the part that really impresses me is how well balanced the Titans are vs infantry.
In most shooters, I am not a fan of vehicles. I find they are woefully unbalanced when up against guys on foot. Either they are fairly balanced against infantry, in which case they don't feel like vehicles at all (much less heavily armored ones), or they are grossly overpowered, making the guys on foot feel like little more than targets to the vehicle pilots.
But TF2 seems to have dealt with this admirably. Titans feel like badass giant robots. Up against a pilot on foot, in a straight up fight, the titan is gonna mop the floor with him. It won't even be a contest. The titans are strong.
But in the context of actual gameplay, the agility and small relative size of the pilots makes it such that pilots are absolutely a major threat to Titans, to the degree that you can't just ignore them. Left to their own devices, pilots can jump on you and steal your batteries.. or do signifcant damage to you with their anti-titan weapons. They need to do it in such a way as to stay under cover and not expose themselves, but once you get a feel for the game, it's no longer the completely one-sided exchange that I would fear it might be.
And the variety of titans is solid. They feel distinctly different from each other, and all seem quite well balanced against each other. The skill ceiling seems quite high, with a good pilot potentially making a huge difference compared to a poor one. The fact that the titans can function autonomously is a situationally useful mechanic, although that auto-titans are really no match for an actual player, even a poor one.
I feel kind of bad that I didn't give this game a look back when it was brand new, and I hope that it has enjoyed enough success to have them continue the franchise, because it's really one of the best shooters that I've played in ages. It definitely shows that the old guys who invented Call of Duty still know what the hell they're doing.