I would argue that even though the surface line has been a regarded as a financial failure, it is one of their most important developments to this date. Microsoft has been developing hardware for user interface design behind closed doors for years, and never released anything to the public before surface. Sure, the surface line was originally pushed by Ballmer, but I am so very glad that Nadella did not just look at financial statistics and just kill it. Hats off to you Nadella.