I still see the "notification center" as a kludgy crutch for the dated, crusty Android and iOS UIs. A properly-configured, personalized Live Tile setup is orders of magnitude more useful.
I worry that ripping off the crust and barnacles from legacy OSes like Android and iOS and slapping them on Windows Phone will hurt usability.
Yes, live tiles do offer an improvement over windowshade notification centers. Hopefully devs start taking full advantage of those capabilities. But there are scenarios in which live tiles are not enough:
If the phone buzzes, and you don't catch the toast, there's no way to see which app had the notification. If all 5 of your lockscreen apps had alerts, it's a crapshoot to figure out which just buzzed the phone, no matter how properly configured your tiles are. In this scenario, swiping left from home to a notification history would be a great solution. But another nice option would be to make the tiles even more live. Have the most recent notifications do something extra to call attention to them, the symbol on the tile could blink, or "breathe" almost like a notification light until it reaches a certain age, or just change color if they have new alerts since the home screen was last seen.
The other scenario is more frustrating. The concept of tiles is about quick glances for info, but if I'm reading an article in IE or a book in Kindle, and i get a toast, I may not pay attention to it, and without a notification tray, i'm back to the first scenario. On android or ios, I can pull down the shade and see what the notification was, without having to dismiss it or leave the app I'm in. That's why going home, tapping on a live tile to get the update, going home, and then having to resume, is a bad alternative. Swiping down from the top of the screen is a really intuitive behaviour on other platforms, mostly due to the almost-always on status bar at the top of the screen. WP8 doesn't often show the status bar, so a down swipe may not be as intuitive without some visual cue up there, such as a solid colored bar across the top pixel row or two, or having a symbol show up opposite the time, if there is a notification pending.
While I do like the WP8 interface, I feel like there are a lot of "form over function" decisions like this that make it a tough choice for many people. If people wanted to be told how to do things, and that the OS knows best, they'd buy iphones.