I believe many things are mentinoned here and there in the forum, so I would share my low moments with the game in rather concise manner:
-Skating is back for another year (even with minimal use of turbo). Footplanting improved minimally, but far from satisfactory. It kills you efforts on defense tremendously.
-Bumping stll excessive and mechanic, improved like 5% from NBA 2K12. A lot of unnecessary and unnatural movements in the game. NBA 2k13 is just another build of the last year game, with questionable improvements.
-Ball awarness by AI players is just horrible. Ball often lands on their head and they stll can't grab a rebound.
-Speaking about rebounds, AI offensive rebounding is basically broken. Its used by the AI to keep scores close or to differentiate dificulty levels in most irritating way possible, another proof of 2k12build not improved enough (boxing out not helping, if you were wondering whether I tried that
http://www.youtube.com/watch?v=u2hQ_WFSiaA&sns=em).
-Dunks impossible to block or change. If opponent beats you minimally for possition forget about blocking.
-Online on pro difficulty is basically an arcade mode.
-Online lag kills your timing for plethora of things, especially on defense. In general online remains the last place where they even try to improve anything.
Well, I hope they address in the patch at least some of things mentioned here, though I remain very sceptical about that. The game is far from trash, it has great positive sides, for e.g. breaking animations in the post, dribble moves are fantastic, but how can you enjoy the good sides when movement, rebounding and other core staff irritate you that often?