The OS and UI
As with other iDevices, you are forced to connect to iTunes (at least v9.1) to activate your iPad before you can use it. While I can sort of understand this, I still think that this is another nail in the coffin with the idea of the iPad being a productivity device and it makes it more of a bigger version of the iPod Touch at this point.
After you do connect with iTunes, you can quickly get all of your iPhone apps synced up and installed on your iPad.
The lock screen is still the same one you see on the iPhone and iPod Touch. Even the "slide to unlock" is the exact same size. Of course, this is because the iPad is using the iPhone OS (version 3.2). So you are getting the same thing that you have with the iPhone and iPod Touch; well maybe a few extra features and/or functions, but still pretty much the same thing as the iPod Touch.
The Dock looks the same, although you can put more than the standard four icons on it; you can drop up to six on the dock. One new thing that is an improvement is that you can operate the home screen (and even the lock screen) in landscape mode. This is very cool and a welcomed addition to the device. However, there is a problem even with this. The accelerometer inside the iPad is very sensitive. I found that when the device was on my lap or on a table a small movement would often change the orientation of the screen and I would have to pick the device up and force it to rotate.
Apple did include a rotation lock switch, but even that has an issue. If you launch an app that has a default orientation of portrait then you get that mode, you have to unlock it, rotate the view and lock it back. It is something of a pain to deal with this.
One thing you will have noticed by now is that Apple has changed some of the menus. As you can see in the image directly above, it is not like the iPhone here. You actually still have the menu of options visible on the left. No more drilling down then back up to move to a different part of the settings menu.
The same UI has made its way to the mail application, although here it might not be as much of a good thing as it is in the settings menu. One of the problems is that if you have an open e-mail in one account, it stays on the screen until you choose another folder or drill back up to another account.
I found this to be a tad annoying. The mail app even retains e-mails you have deleted until you move to another folder (if there are no other e-mails in the folder). Speaking of the Mail App and things that need to change, I wonder when Apple will let you have a signature for each e-mail account, like many other smart phones/devices do.
One of the nice items that Apple has thrown in (obviously to combat the jailbreakers), you can now change the wallpaper on the lock screen and the home screen. You can do this independently or use the same image for both. This is not the same as being able to change the entire theme, but it is a baby step in the right direction.
As was shown at the launch event, there is a new feature called "Picture Frame". This lets you turn your iPad into a 9-inch digital picture frame when you have it locked. It is a pretty neat idea and one that I played with a total of four times in two days. I have not used it since and after thinking about it, a $500 digital picture frame is something of a joke anyway.
Overall, the OS and UI are really identical to the iPhone and iPod Touch with a bigger screen and better resolution. I wish there was more to say about this, but there isn't at the time of this writing.