It depends on the user.
In my current situtation the Wii U is a decent console. I mainly play games on my PC and my Wii U compliments it perfectly. For me it has a much better library of games than the ps4/xb1 does because I can already play 99% of the ps4/xb1 games that I want to on my PC. The fact that it doesn't have any third party support is meaningless to me.
On the other hand I can't even imagine only having a Wii U for my gaming needs. I would estimate that I've gotten about 200 hours of gameplay from my Wii U a year. Certainly not enough content for it to be my only gaming device. The library is just too limited. Nowadays I only use it when friends come over.
For someone who doesn't plan on owning multiple consoles or a gaming PC, I would agree that the Wii U is the worst choice for this gen. But it is a great compliment to a PC/PS4/XB1 for those that plan on buying multiple devices.