Speaking to Gamesindustry.biz, devs queued up to say that Wii U just wasn't up to the graphical standard of Xbox 360 and PS3.
"No, it's not up to the same level," one said. "The graphics are just not as powerful."
"That's true," said another. "It doesn't produce graphics as well as PS3 or 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."
One developer highlighted Wii U's support of a single tablet controller as another flaw. While reports late last year claimed Nintendo was working on supporting multiple tablet controllers, it appears developers are still working on the understanding that only one player will be able to use Wii U's input device.
"The whole thing about the tablet controller is that you only get one of them, and you can only use one and it's not completely independent," the source said. "The base console has to be on, and you have to be in range.
"Other controllers are just Wiimotes, or other Wii controllers. They may change the form factor or looks a bit, but it's the same controller."
Worrying stuff, and it's in stark contrast to recent comments made by Capcom's Yoshinori Ono. The Street Fighter producer said in January that the Wii U had been much improved since its unveiling at E3 last year, saying the latest version of the system had "many unique possibilities."
Epic Games VP Mark Rein is also a fan, saying last month that "we've yet to see what Wii U can really do and I think at E3 this year they're going to shock us." Nintendo is to unveil the final Wii U hardware at the June conference, with the console due on shelves before the end of the year.