Spec wise/ capability it is a good system. It isn't receiving any support because it's too late to a market dominated by Nintendo and smartphones.
Wii u is a great system with great games but is a victim of its own kiddy image and lack of respectable online options.
A great system could stand on its own. Meaning you could buy a great system and have it be your only system and not feel like you're missing out on much.
If a Wii U was your only system you'd miss out on a majority of the great third party titles that come out. You'd maybe get 3-4 titles worth buying a year and that's it. Best case scenario the Wii U is a secondary system.
As for the Vita it failed outside Japan because its a poor portable system. The Vita strives to bring you a Playstation experience on the go. That's what's wrong with it. Most people don't want to play console style games on the go.
I'm not a fan of the Vita because it splits the market just like the PSP did. Games like Last Ranker, God Eater, Ciel nosurge, and The Legend of Heroes series will come out on the Vita / PSP but since it isn't a viable platform outside Japan they don't localize the games.