It's pretty lame. Samus isn't in as strong a pose as on the first game's cover. That was a better piece of boxart. It announced the long-awaited return of Metroid with a bold render of Samus standing tall (looking distinctly 3D, a selling point for the series).
On Echoes' cover, Samus looks like she's taking a dump.
At least get Dark Samus on there, an enemy, a cool background, something. THe half dark, half light motif is not that provocative or striking to the average shopper who isn't familiar with the game's premise.