Yeah that's a fair assessment to be honest. They both are good solid hardware with a few great games and a ton of wasted potential.
I feel also that both could have benefited from some removed stuff... On the Wii-U a Wiimote or regular controller would have been better than the screen controller thing... (made it expensive and didn't add much) on the Vita side of things, I feel like the rear touch pad and proprietary memory cards added a lot of expense for almost no gains.