NBA 2K13 is an unbelievably well done game. It has multiple online modes including the Association, straight up 1 on 1 team games, and Team up 10 person multiplayer where you play as 1 player in an NBA game with up to 9 others which is great fun. It also has Blacktop mode which allows you to put your MyPlayer creation up against others in a 3on3 streetball mode which is great too. This game is an improvement on pretty much all 2K games released. I even like it slightly more than 2K11 which was also a great entry into the series. The way they chose to map controls to the right stick in 13 is far superior than any other entry on the series. It adds just enough simplicity to make the more difficult moves doable so you won't end up never doing moves based on having to hit 5 buttons at once. That is a thing of the past now.
The animations, ball control, and passing are also much better than the last several entries. Driving to the basket finally does not feel clunky, and you can do it without constantly worrying about a charge. You can alter your intentions of a shot or pass or dribble on the fly with the right stick and shoulder buttons. The play calling system is also by far the most effective and usable it has ever been in 2K. You can fire up this disc and have an excellent time playing just straight up basketball in almost an arcady sense, or play full on in depth simulation all the way down to each and every play and coaching mode and also have great enjoyment. Commentary is spot on and your AI teammates almost always choose correct shot types and go for the higher percentage looks.
Only minor things I would change:
The VC currency system is kind of a drawback. They obviously did it to cash in on microtransactions and it is not that big of a deal, but it is kind of annoying when you go to play against someone, and they have played 5 or less games but control a maxed out character simply because they spent 10$ on VC. Sort of defeats the purpose of 2K's excellent attribute system, and you see it A LOT.
This one is just personal to me, but I HATE the Jay-Z influence on the game. I find it really annoying hearing his songs every single time I boot up the game and constantly when I am working in the menus. I also don't really like hardly any of the other artists he chose or the art style with all the flashing lights and over-the-top-ness, but hey, maybe that's just me. I guess it is better than silence, but only slightly.
Also, easily the most annoying for me, when you play Blacktop or Team Up online modes, almost everytime you or anyone else takes a shot it lags out for a .5 to 1 second. Literally almost every time, and usually only when shooting is occuring. It makes timing and defending jump shots in these modes difficult due to technical failure not skill. In the standard 1on1 NBA team mode I never see this though which is good. That mode which is the main mode runs perfectly with zero issues.
In closing, 2K13 is a great game and easily the best basketball Simulation of this gen. It is one of the best bball games ever made actually. I would only put NBA JAM, NBA Live '95, NBA Street 1, and NBA JAM on Fire Edition ahead of it in terms of entertainment value, all time. Maybe one of the first few 2K's also.