Given how great the NHL team was with their patches last year, I wouldn't be surprised if some of NHL 10's issues get addressed early-on with patches or tuner sets.
Right now, though, it looks like EA has their hands full trying to fix the overloaded online servers.
Guess they didn't learn their lesson from last year's server fiasco.
We were able to get our review of NHL 10 published in time for launch day because EA was gracious enough to send us a reviewable copy two weeks in advance.
Unfortunately, 2K's game arrived in our reviewer's hands only a few days before launch, so we will probably have to wait until late this week or early next week before the 2K10 review is ready to go.
That said, since there's no demo this year, my experience with 2K10 is limited to watching videos of it online, so I don't have much basis to make a comparison between the two games aside from how they look graphically.
For whatever it's worth to you, I'm still having a lot of fun with the NHL 10 offline modes (mainly Be a Pro) even in spite of its flaws.
There are moments of frustration for sure, but overall, modes like Be a Pro are still a great experience.