In addition to the console versions released today NBA 2K14 has also arrived for iOS devices (download from iTunes here) for $8. That is the same price NBA 2K13 released at on mobile to generally poor reviews while other companies have instead been trending towards the free-to-play model. It is not yet out for Android but expected sometime this month.
Unfortunately 2K Sports did not provide any details on app features so at this point users would be buying blind. NBA 2K13 featured the NBA’s Greatest mode and presumably like the console editions that will be gone in favor of a Path to Greatness mode centered on LeBron James.