It is attractive for me at this stage (no fee). It's difficult maintaining 2 online subscriptions for 2 systems (worse for 3), and that's after purchasing the hardware, games and peripherals.
If their infrastructure is up to par with XBL or provides value like PSN then I would not mind paying for it in the future.
At this stage I probably would not pay for it since I already have to pay for PS+, and I only see myself playing Nintendo exclusives on the Wii U, and currently they don't support much online play. However, if they did charge, I'd gladly give them my money to enjoy Smash Bros. Wii U online. I'm probably going to sink more hours in that game than every other title on any platform combined, so I might as well pay for it lulz.
Playstation = The Beast from the East
Sony + Nintendo = WIN! PS3 + PSV + PS4 + Wii U + 3DS
