Being a computer geek, I have a fair few gadgets. Recently I acquired a Kindle (and I already have a Sony Reader). The Kindle and Sony are really very similar, but recently there are a few books/magazines I have not been able to get outside of Kindle format.
What's interesting to me is the different way these devices handle PDFs. Because PDF text is generally too small on these devices, you have to zoom in. The Sony will actually resize the font and re-paginate the text, which is clever, but the carriage returns get messed up and so do the images. The zoom feature on the Kindle literally just zooms and you have to scroll around the screen to read, this seems horrible at first, but the trick is to zoom to 150% and go into landscape mode, then you can just read downwards using the normal page turn buttons. The problem on the Kindle is that it then remembers this mode when you leave the book, which is annoying. The Kindle badly needs to remember zoom settings specific to the book - hopefullly this will be in a future firmware update. I think both devices could really do with a bigger screen, preferably a touch screen (iPad style) to give more screen space and get rid of the buttons, then maybe you wouldn't need to zoom in the first place. They could also both use an accelerometer for portrait/landscape mode and a backlit display that you can turn on and off, but they can't give you everything at once or you wouldn't buy version 3.0 (actually Sony have brought out a backlit model now).
Despite it's naughty proprietary "buy everything from amazon" nature, the Kindle does have 3 things going for it:
i) it's cheap,
ii) you don't have to use the horrible Sony Reader Library software to transfer files (you just use windows explorer), and
iii) it's got wifi (3g on the expensive one).
At any rate, this brings me on to a couple of things:
1. I'm probably very slow on the uptake here, but today I discovered that you can download MSDN Magazine for free in PDF format from here: http://msdn.microsoft.com/en-us/magazine/ee412244.aspx (Some of the older ones are in .chm format though).
2. I really dislike proprietary formats. They are anti-competitive and try to tie you into a device or service. This is why I regret buying an iPhone instead of an Android, and why I will buy as few books as possible in Kindle format. I guess you can convert Kindle format to PDF with some third party tool if you have to, but in most cases if you go to the publisher's website you can buy the PDF/ePub version direct from them (at least in the case of technical books).
In terms of proprietary formats/software, Apple is by far the worst offender. How on earth Apple has managed to get away with so many propietary tie-ins when Microsoft has been consistently dragged through the courts is beyond me. Their spate with Adobe over Flash on iPhones is hilarious too. I'm on Adobe's side on that one, but only because they opened up the PDF format ;c)
I originally bought my iPhone to play with some iPhone development, but the proprietary dev tools and Objective-C language seemed totally archaic compared with the Microsoft development world. On the plus side, they have subsequently relented and allowed other developer tools (http://gizmodo.com/5633721/).
One last thought. Computer books are quite frequently huge (1500+ pages). Books don't attract VAT, but electronic books do. Aside from this strange philosophical approach to tax, the UK government isn't really saving trees on this one is it? Computer books go out of date fast too, so it's not like 20 people will read the same book.
Edit: By strange coincidence, just 5 mins after I was writing this, I got a phonecall from one of my brothers. He told me he had just got an Android phone. I asked him why he had chosen it over the iPhone. He said his IT friends would never have forgiven him for buying such a proprietary device! Oh, he also said that iTunes is one of the worst pieces of software ever written. I'm not sure that's true, but when you consider the money invested in it and the flagship nature of the product, yes, it really is awful to use, especially from a company known for their user-friendly operating system. At the end of the day though, the iPhone is a lovely piece of hardware, nobody buys it for the software. I know plenty of iPod users that stay away from iTunes altogether. Personally, I hate iTunes, so my contacts are sync'd with Google and my music is sync'd with MediaMonkey (which I recommend). So, just because iTunes is horrible isn't a solid reason not to buy an iPhone, you can just avoid using it altogether (except for firmware updates).