The new picture is better than the first one.
The original had a dark background with brightly lit characters in the foreground. The background unfortunatedly "swallowed" the characters. Also, the "camera" was front-and-center, and the colour scheme was too gray (gray background, gray armor on the woman, muted colours on the tiefling).
The new picture has a bright background that bumps the characters to the forefront with their high contrast and deeper shadows. The "camera" is set on a lower angle, so you are looking up to them a bit. The bright blue background contrasts nicely with the bright red of the wizard's robes and the darker shades of the dragonborn's armor.
I attached a slightly enlarged version of the cover.
I still prefer the "Green Dragon Fight" cover. It draws the eye much better from a distance (in, say, a bookstore), and the nice homage to the earlier Erol Otus cover would garner 4e some measure of goodwill from older players.