I have a lot of fond memories of the Wii U, and in many ways, I regard it as a party system. The Gaming Club at my University got a lot of mileage out of Nintendo Land, Game & Wario, Mario 3D World, Sonic Racing Transformed, and of course, Mario Kart 8 and Smash.
Personally I like it more than the N64, and I think most of the games that originated on it will age better too.
Opinions: NES/Famicom & Switch > SNES & GC > Wii > Wii U > N64 > Virtual Boy
But yeah, Nintendo only has themselves to blame for it's failure. I think it's a solid system overall, but poor marketing, very little was ready to go out of the gate (yet another NSWM game? that's your system seller?), being under powered, and hard to develop for doomed it from the start. 2013 & 2014 were solid hype years for the system, but the writing was on the wall.
I'll be curious to see how it does in years going forward. It has a small physical library with only a couple games going for over $100 CIB, lack of sales and the Gamepad factor, I think will make it a very interesting system to collect for. It will especially be an easy system to go for a complete set for; complete might only be $2000 ~ $3000.