Not grandparent, but will try to answer anyway. I do mostly scientific software development and analytics for a bioinformatics lab. Being able to carry around all the academic papers I need with me at all time, together with supplementary material and online manuals in PDF form, is tremendous for me. What's even better, I can highlight and make notes right in those PDFs with GoodReader. Unlike most other eReaders, iPad has a color screen, and in my field (computational biology and genetics) this is crucial as nearly every paper published in the big three (Nature/Science/Cell) has complex color diagrams in it.
I have been using Penultimate (notebook-like app where you can scribble with a stylus) to lay out nearly all of my ideas. Because I develop algorithms as well, only being able to type (as on a laptop) is not good enough for me. I need to be able to jolt down diagrams/drawings with a pen/stylus all the time. I can immediately email any of my notes/diagrams (or the entire notebook) as a PDF file to collaborators that I have in my Contacts list in the Mail app. I don't have to carry around several unwieldy notebooks in my bag anymore. The only things I carry in my messenger bag now are: MacBook, iPad, vacuum flask with hot coffee (if the workstations at work were Macs, I wouldn't even have to carry the MacBook). No more paper!
The iPad has VPN and an SSH app, so away from work I can login and view how my clusters are doing.
I am able to do the things I listed above on a single device (except software development). The reason I carry around a MacBook is only because I compile code at work for Linux platform and I like to have a second non-Linux but UNIX computer to check code portability, which I wouldn't be able to do with Windows anyway (don't get me started on Cygwin).
1. PDFs are much easier to read on a vertical-format screen unless said screen is very large (would need to twist modern wide-screen laptops sideways). Also, I prefer that my reading device is not heavy and that it is small enough to read while on standing on public transportation -- this way I can get heads up on things before arriving to work.
2. The ability to annotate documents directly using finger input is amazing (I am not talking about handwriting -- I am talking about yellow-highlighting passages and keywords without using the classic trackpad and cursor combo which requires a stable platform for it to be usable).
3. The ability to just take the PDF/document/notes/whatever and bring it over to my boss next door is irreplaceable. Laptop is too heavy and cumbersome to hold with one hand, and email/file-sharing is cumbersome as well -- bosses are generally unwilling to listen to their subordinates tell them to open this or that file while they are in the middle of something on their screen. This is why most offices have stuck with paper for so long -- it is great to be able to carry something in your hand and just show it to somebody across the floor. Likewise, it is easier for my boss (who also has an iPad) to just show me some document without having to print it or email it to me or walk me over across the lab to his computer.
"Laptop is too heavy and cumbersome to hold with one hand, and email/file-sharing is cumbersome as well -- bosses are generally unwilling to listen to their subordinates tell them to open this or that file while they are in the middle of something on their screen."
The importance of this is under-recognized.
A friend realized it is much cheaper to just pre-load an iPad with demo software and mail it free to a prospective client, than to fly to said customer and arrange for meeting times and persuade them to load & run software on their computers. Open an envelope, turn it on, start using the product - send us a check and we'll keep it on and send you more. "$500, it just works" is _cheap_ for what it buys.
I'm a software engineer by day, and a software/hardware hacker at night also working on my own start-up. I require reference to be easy and without lag. Once I build up a flow of thoughts and ideas that I've compiled from a list of sources, I like to be able to reference them and organize them without having books lying about everywhere.
I recently learned Objective-C pretty rapidly by having access to multiple books at the same time and consuming them in parallel. When I would have trouble understanding one concept in one book, I would move to another book that could explain the concept better to me. So I was book-sourcing my learning.
iBooks is sufficient for this, but I've been thinking about building my own tool that processes information the way I do and keeping the journal handy.
My set-up is (left to right): 27Inch Cinema Display, iPad on stand, MacBook Pro.
I use my cinema display for coding and browsing, the macbook for logs/stderr/stdout, and I use the iPad as a book reference. So I can flip back and forth around the iPad if I need to, or I can take my iPad to another workspace on my workbench and not have to deal with lugging my laptop around.
I teach part-time. Being able to use an instant-on, anytime-anywhere networking device lets me juggle an extra class amid whatever sporadic 5-15 minute breaks I can find. My iPad paid for itself in 3 weeks.
