Right out of the gate they disliked the underpowered CPU
Eurogamer recently hosted a first-hand account from a mystery developer, which describes the Wii U development process in great detail. It's a page turner for sure, going through the entire process of making a game for the Wii U, from the "studio visit" from Nintendo when it was "Project Cafe," to early development woes, to the rush for the day one patch, to the "less than impressive" sales figures.
Interestingly, the developer also pegs the Wii U's launch woes partially on brand confusion (Wii vs. Wii U), and "bad timing," as the PS4 and Xbox One were hyped mere months later -- when many developers were already excitedly working on them. One of the biggest shockers in the report however is the allegation of a complete lack of understanding in the online realm.
When speaking on the online functions of the system and trying to make helpful comparisons between existing infrastructures like the PSN and Xbox Live, they ran into trouble. The developer states that during a conference call with senior Nintendo officials, that they were told to stop referencing the PSN and Xbox Live because "nobody in their development teams used those systems."
This is all fairly interesting information for anyone who wants more insight into the development process, as I'm sure many console manufacturers and third parties have gone through the same difficulties when creating a new platform. I hope the Wii U recovers more as 2014 goes on, but based on what this developer is saying, many studios have moved on and decided to work with the PS4 and Xbox One (which they refer to as "real" next-gen consoles) instead. As always, take this with a grain of salt.
The Secret Developers: Wii U - the inside story [Eurogamer]