I'm not a big CoD fan, but I'm not seeing the comparisons to CoD at all. The shooting/gunplay mechanics looks VERY similar, but given that the maps have to be signed for regular players AND mechs, the chances of this being a game that focuses only on close-quarters are pretty low.
Imagine what adding double jump would do to CoD. You go to line up your iron sights and he jumps over your head. Already a different game.
Supporting Titans and wall-running require new map dimensions. It really is its own thing.
We have some old school shooter guys on the Respawn design team. I was making DOOM and Quake maps professionally via contract when I was in college, and our Game Director and I both made official Rocket Arena maps for Quake3. I was one of the founders of QuakeCon and I went every year through 2006.
In many ways, TF is a blend of the best of modern and old school shooters. One of the original design goals was to bring back projectiles, instead of being almost all hit-scan based weapons.
Wall running is sort of like an accessible, hand crafted version of diagonal running in DOOM and the strafe jumping in Quake.
Speaking of wall running, it has existed in TF since August 2010. The influence for wall running was not from games, it was from Kick Ass. I quit IW on 4.12.10, and Kick Ass came out later that week. I saw it in theaters and couldn't stop thinking about wall running and shooting in an FPS.
This scene stood out:
http://www.youtube.com/watch?v=vsBKyduk3RE
Watching it again for the first time since seeing it in theaters, she doesn't really wall run that much, but in my head she did.