updated 30sep2016
Mechanically, my Kindle does a fair job of displaying text, not so great at images. A laptop considerably is better but if it's running the Kindle application, it's substantially not as good as what I normally get in a .pdf. Print books have limitations also. The format whether print, pdf, doc, txt, or some proprietary Amazon format is probably more important. It's still important to understand the differences and long term implications, but in the end, the content is what's important and the mechanics can be reguarded as enabling or hindering access to and use of content. I want to first dicuss the fluff stuff including DRM and then talk about what I'm reading.
I want to discuss how I'm reading now - basically the physical access to content. I'm interested in how phsical access (phone, kindle, notebook, etc ...) changes what I read and how much I read. The publishing and distribution of literature, music, and video is changing dramatically and I think large companies want to control - not just what we read, but how we get it - mainly for profit, but also to manipulate public opinion (look at how the new media runs the same stuff). of the various media and the whole thing about whether the content or the delivery mechanism is important and make it a page by itself. Also interested in how (or if) the physical media and delivery mechanisms changes how or what I read. Content is king, obviously, but the delivery mechanism: kindle, pdf, or text makes a significant difference. Considerations are availability: how can I get the material, how easy is to view, how easy to index, make notes, etc ... Of major consideration is rights management - technically and ethically.
Retirement should enable me to read very different books than I did while I was working - at least more of them. I think wanting to use the Kindle will help that too since it's not conducive to technical stuff. My feelings about the Kindle are getting more firm. It's definitely a limited purpose device - but it's so darn convenient to just be able to pitch it in what ever bag or even pocket. I don't want to write book reports or reviews. If someone wants to talk about any of them, send me an email. I probably won't include everything - I also finished a Terry Prachett book called Snuff on the Kindle (everyone should have already read some of his books).
What I've said before about the Kindle is borne out by reading this book (Data and Goliath). It's great for sitting down and reading. It's a fair paper book substitute (with some serious privacy concerns), but it's no computer. I'll continue to use it because it's convenient to carry around, but I need a separate notepad and there's no savings on the cost of the books. The O'Reilly model is really much better in almost every way. Maybe I'll look at the whole publishing thing sometime.
The kids (all of them) got me a Kindle. I charged it up in a few hours, connected it to my WIFI and within minutes had charged $40 in books. It's wrong to make this so easy. I never allowed that to happen with my tablet or anything else. It's far too dangerous for a device with so many limitations which is something worth exploring in great detail at some time). But I'm under the gun to get a lot of work done (since I now have a contract on the house) and the details of this are going to have to wait. I'll put up some pictures for entertainment though.
What it's like with furniture gone.
The Kindle is small and easy to keep around. It's great for poor light situations (really great). The significant negatives are: situations where you're studying and have to deal with multiple refereces and making notes - it's just a failure; then the pecular file format - I just don't want to futz with getting it to work on my Linux notebook. It's only advantage over a notebook are small size (ah - and battery life - it really shines).
I'm reading The Autobiography of Mark Twain and here's how it compares with the Kindle: 
. When I take a book to bed to read, you can bet it's on the Kindle or a tablet - actually I'm using the Kindle for all light weight reading now. There are a few paperbacks left, but when they're gone, I won't get any more.
The phone carries the size thing to an extreme. On the plus side, it's almost always with me, it's reasonably easy to see in most lighting conditions, and it comes with Polaris Office and can read .pdf files. But overall it's too fiddley to read very much on. If there was a really good way of indexing documents and finding things, I'd probably use it. As it stands, it's just not something I want to do a lot of reading with.
I suppose this is the elephant in the room. Rights owners are trying to tie things up in knots and may very well succeed and in the meanwhile, content consumers are not allowed to take part in the discussion. At every level you read about this stuff, there is no mention of the rights of consumers, just every consideration to how large holdings can manipulate things to maximize their gain. Stuff like this is bound to happen as these old things age and I expect that there will be some deliberateness to the aging process. It could even be selective. I've lost material I purchased for my handspring PDA yeas ago because it was encrypted and the key is gone.