Impressions from the first hour:
Well, they redid the entire intro gameplay (getting to the bunker). It's clearly a retelling as if Frank did everything, but a lot of the events are twisted - instead of racing there is a "wrestling" battle royale, instead of looking for Katey there's a stealthy photo shoot, etc. Overall I say it feels more "Dead Rising" to me (particularly with the camera), although I can't really tear it away from what I remember of playing Chuck through DR2.
(There's an immediate unlockable if it detects a DR2 save, by the way.)
As far as I can tell, this game is DR2, just altered wherever possible to fit Frank. So it's definitely not a swap job - clearly the story sections have all been heavily modified to fit, there's a lot of new dialogue - but it's Chuck's bunker, Chuck's escape route, Chuck finding Zombrex (although obviously for your own use, not for a little girl). Although obviously with a new zone and new combos. So probably won't branch off a lot for awhile yet.
Oh, and all of Frank's lines could have been taken from the first post of any GAF-NEWS thread.
Checkpoints: These only work while the game is on so I can understand why they did it. You can always ignore it and go back to a save, and you're still required to save between sessions - still, it is definitely another step away from the roguelike sandbox, even if it's a small one.
Menu System: Much improved, more responsive. Except for the save system and startup menu, oddly enough - those are as stop-go as ever. But ingame is great. Although, another change away from the roguelike sandbox is that there is no longer a "FPS watch" view. As far as I can tell, you can see Frank's watch (a digital) in the corner of the map screen and that's it.
All in all it's huge dose of "I've played this before" once you get to the freeroaming, but the story stuff is fresh. Will be interesting to see if Chuck was written out altogether...(if so, they may as well redo Case Zero and Case West...)