According to Jeremy Parish of 1UP, Mass Effect 3 on the Wii U has technical issues. He explains:
This version of ME3 seems a lot less visually stable than, say, the Xbox 360 version — the frame rate is choppier, the animation seems rougher. The audio suffers, too; while the music and sound effects have come over fine, all the dialogue has a hollow, echoing quality to it.
Combined with the fact that the future downloadable content might not be released for the platform, this version of the game is appearing less and less appealing as time marches on.