Nintendo's new machine is "not up to the same level as the PS3 or 360" and is less powerful than Sony's PS3/PS Vita combo, according to a number of developers.
"No, it's not up to the same level as the PS3 or the 360. The graphics are just not as powerful," an unnamed developer told Gamesindustry.biz.
A different developer at a "major company" echoed the sentiment, saying: "Yeah, that's true. It doesn't produce graphics as well as the PS3 or the 360. There aren't as many shaders, it's not as capable.
"Sure, some things are better, mostly as a result of it being a more modern design. But overall the Wii U just can't quite keep up."
Prior rumours have suggested the Wii U could be anywhere between twice as powerful as an Xbox 360 and similar in power to the Xbox 360.
It is speculated that a lack of graphical flair is one of the side-effects of keeping the price down at retail, especially considering the manufacturing costs of the Wii U's tablet controller.
The news comes after a report suggested that the Wii U would launch on November 18 in North America and one week later in Japan.
Nintendo is expected to announce release details for Wii U at E3 2012 this June.
Watch the Wii U concept trailer below: