The firm has compared it unfavourably to its PlayStation Vita, which it says can do "some pretty special things".
"That Wii U tablet doesn't have a processor in it, so it's got to be fuelled by that box sitting under your TV," Sony's Scott Rhode told GamesIndustry International.
"We can do some pretty special things that you'll start to see on the [E3] floor this year and you'll see more over the upcoming months about what you can do when you actually have a processor in the thing that's in your hand as well."
Rhode also came to the defence of the PlayStation Vita when pressed about the console's sales.
"It's only been three months though, just three months. There are a lot of games on that machine and I think what we have to hang our hat on... Every single person that actually picks that thing up absolutely loves it.
"Look at two of the titles that are here at E3, PlayStation All-Stars and Sly 4, for example. Both available on Vita and PS3, and there's some sort of interactivity across the board. Developers are interested in that kind of stuff."
Sony unveiled Assassin's Creed: Liberation and Call of Duty: Black Ops: Declassified at the E3 Gaming Expo, while Nintendo announced the Wii U's final specifications and software list.
Watch the Wii U Gamepad video below: