You'd think getting into a Titan would slow the game down, but it's actually quite the contrary. The mechs are big and powerful, but also quick and maneuverable. They have just enough HP that you can take out an enemy mech with your own in just a few seconds if you know how to circle-strafe like a pro, yet won't fall so easily to simple attrition. Cool little touches, like squishing enemy pilots who spend too much time near your feet, or ripping an enemy pilot out of his downed Titan as an "execution", really help make you feel like a badass.
On the other hand, seeing an enemy Titan as a pilot shouldn't make you run in fear, it should make you think, "how do I take this mother down?" Using the aforementioned double-jumping and wall-running to get the high ground, and literally jumping onto an enemy Titan's back to blast him where he can't hit you, is just as cool and rewarding as being the Titan yourself.
Titanfall is a multiplayer only game, but it does have a little bit of singleplayer "flavor" thrown in. Each round is a "mission" complete with objectives and regular voice-over updates from NPCs, and at the end of the mission, the losers will have to evacuate while the winners try to wipe them all out. Either escaping as a loser or stopping the enemy from escaping as a winner will net you a considerable XP bonus.
What I did dislike was the abundance of bots in the demo I played. Since we were only playing 6v6, quite a lot of those pilots I was squishing beneath my giant metal boots were AI controlled bots who would simply run at me with little regard for their own lives. Hopefully, the retail game (at least for the PC version) will allow us have huge 32-64 player battles.
Titanfall is shaping up to the the shooter of the next generation, offering up enough familiarity to shooter fans who wet their feet with CoD, and bringing back the speed of fast-paced twitch-shooters that oldschool Quake fans have been yearning for.