The trailer showcases a style much like 2.5D platforms video games. We mostly see Snoopy and Woodstock walking along a flat plane, modeled similarly to the original drawings. The limited animation and perspective is charming, and the moments where the overall feel is broken benefit the story rather than feeling lazy.
Blue Sky is clearly out to honor Peanuts with the work they've shown so far. If the final product remains this charming throughout, we've got ourselves a real treat coming in 2015.