For note taking the iPad has a bunch of nice apps. It is one of the main reasons I got one. Taking notes on a laptop is OK if you have a place to type. Most of my notes are done at customers while talking face to face. Typing on a laptop becomes impersonal. I wanted a more natural note taking device.

For Calendar and Email the iPad is a good choice - especially if you don't need all the fancy features (also depends on what kind of groupware you are connecting to)

Downside is as mentioned above - not a full fledged laptop, that being said I find myself reaching for the iPad more than the laptop in day to day situations. Easy to use, most websites come through well (flash of course is the exception, but if you are burning for flash you could always try cloud browse in a pinch)
Cloud Browse - Use Flash and Java on iPhone and iPad | AlwaysOn Technologies

Here are the note takers I like
Recommeneded but haven't tried
Awesome Note - Brilliant Idea

Great for handwriting (not recognition) Has a zoom type window
Note Taker HD for iPad on the iTunes App Store

Writepad - for handwriting recognition (not good for drawings)
WritePad for iPad for iPad on the iTunes App Store

Penultimate for drawing type notes
Penultimate for iPad on the iTunes App Store

Smartnote - general purpose note taking
smartNote for iPad on the iTunes App Store

Noteshelf - another general purpose note taking with templates
Noteshelf for iPad on the iTunes App Store

Corkulous for brainstorming
Corkulous for iPad on the iTunes App Store