Prior to iOS 5, Apple's iPhone and iPad notification system desperately needed updating. Since the advent of Push Notifications and background multitasking the old, outdated model alert system had become more interruption than notification, more annoyance than advantage.
The challenge was to make alerts powerful enough for advanced users while keeping them simple enough for Apple's mainstream user base. Like with folders and fast app switching, they chose to make it a hidden layer of the iPhone's interface, something that could be called up by users who know where it is, but could be just as easily ignored by users unaware or uninterested in its functionality.
And it does a pretty good job. Banners alert you to any incoming messages, far less obtrusively than the old style pop-ops (which still remain for more attention-demanding alerts like appointments and alarms). Notification Center provides you with a pull down shade listing all your recent alerts, and can do so on the Lock screen as well as in apps and on the Home screen. It also stays out of your way when you're not using it, for the most part.
But such compromise is inevitably compromised. For advanced users, there's still no quick settings access, message previews, in-app replies, or widget support beyond the built-in Weather and Stocks apps. For mainstream users, there are banners that cover their buttons and shades that drop down after inopportune swipes with long lists of messages that are difficult to dismiss. (Tiny tap targets much?)
So is it the right compromise, or just the right compromise for now? If you jailbreak is it good enough to replace IntelliscreenX or LockInfo? If you come from Android or webOS, how does it compare? If actually using Notification Center is the best way to judge the usefulness of Apple's implementation, how often do you actually find yourself using it?