This is wrong. I haven't really been following DayZ that closely, and even I can tell you they've accomplished way more than that.
From the brief videos they've shown of the DayZ standalone, they've taken the ARMA engine and optimized it completely for DayZ, they cut out all of the unnecessary background processes and code, re-wrote a large chunk of the netcode, redesigned many parts of the terrain, completely overhauled the UI, redesigned every single building to have an interior, completely re-created the lighting system, created a whole new loot spawning system, mo-capped new player and zombie animations, created new player models and enemy models, recorded new audio, added new vehicles, and probably some more stuff I don't know about.
Saying all they've done is "new skins/pathing" is beyond exaggeration, to the point of dishonesty.