Brawl's looked very stiff honestly, a few of them like Samus and Meta Knight's were good, but then you had guys like Mario, Link and Pit that just look dead in their eyes.
The Smash 4 renders are much better, they're much more lively. I will say that I don't particularly like the Palutena, Pac-Man, Kirby, Diddy Kong and Samus renders though. Palutena is just the same as the KI:U artwork, likewise with Pac-Man it's just the same old boring pose, with Kirby it's just odd to have a character sit down like that on the select screen, something looks off with Diddy Kong's mouth, and Samus' is way too static compared to her Brawl render. I also think Charizard's looks weird, what the hell is he even doing? It looks like he's about to fall over or something.
In general they're still much better than the Brawl renders though. I mean, just look at Ike, he looked like one of those action figures with bendable limbs, now he's ready to kick some serious ass.
I love the renders.....they are all very creative and they definitely stick in my head. And people should cool their jets about Palutena...It is just pre-game after all, it could change. If I remember correctly, wasn't Mega Man's face during his final smash at the demo very dull, but in the direct it wasn't?
In-game animations and renders are two very different things. Renders are used promotionally and have to be finished much earlier to fit the CSS, stock icons, and so forth. It's not changing this late. The only time we've seen a render change mid-development was with Pit's Brawl render on the 2006 Brawl site, it was changed when his page went up on the official Dojo in 2007, and that was still only his face.