Two small notes. One of the interviews with Steve captured quite an adorable moment which indicates how he played Hammy.
"Steve Carell, who is the voice of Hammy, observes, "Hammy is tremendously loyal to his friends; he is very kind and very loving. It's going to make me cry just thinking about him because he is the sweetest thing. " Taken from: http://www.animated-news.com/archives/00005062.html
As for the humans, the design reference for the movie was with the animals being the normal 5-6 foot height. All of the humans were made to be huge giants (as well as the world). This allowed the layout team, lighting and modeling to make the humans look incredibly massive and towering. That is why they look strange to everyone. Dreamworks did this to help the audience sympathize with the animals (which look normal) instead of the humans.
Over the Hedge was in development for four years and the quality, quite frankly, shows. I would not grant it in the same level as Incredibles only because it lacks the intense family emotional power that Pixar invests in their movies. It is a highly refined and appealing movie.
For those interested in animation as a technical field, pay attention to the careful use of focus-pulling and wide apature lenses to give the movie an unexpected scale that the majority of the audience will subtly inhale but not notice. This movie marks the first time specular highlights (? unclear on this) were used on individual blades of fur (seen on Verne and Stella) to grant their fur an appropiately glossy texture. Also watch for RJ's fur to emote in response to his actions and feelings. This is best seen in the start when he breaks his grabber and his tail bottle-bristles. High-Dynamic Range modeling was used heavily in the scenes involving groups passing through the hedge. The best example of this is Verne first walking through the Hedge into the backyard.
For the budding animators here, this is Dreamwork's highest quality work to date. They expended a great deal of effort into the facial expressions. RJ is particularly powerful while emoting visually. I have a difficult time saying that The Incredibles (/ Monster's Inc) or Over The Hedge had the best use of facial rigging to convey emotions; however, there is no doubt a great deal of work was invested in the characters. Things to watch for: RJ's personality expressed through his strutting and gestures (What's that? That's an SUV.), squash-and-stretch on Hammy's expressions, keep-alive on characters (breathing), grass deformation by walking (for simulations), and facial expressions on all characters.
If you haven't seen it, go out and enjoy it. It is a wonderful introduction to the summer.