I will tell you what the problem is. People see the Wii-U and think ''wow great, a tablet with buttons that plays Nintendo games!''. Then the realize you can only use it with the console nearby and then they think: ''Why would i need this if i already have an IPad that enterntains the whole family and that i can take anywhere?''.
It might sound a bit bashy but it's the truth. The only advantage the Wii-U has over other systems is the tablet controller, but most people i know already have a IPad or other tablet. Also the Wii's advantage was that it introduced an ''active'' type of gameplay for the whole family, that's what made it sell.
Nintendo was on the right path with the tablet controller idea, but it should have been an stand-alone system that you could use anywhere.







