When we are considering the purchase of a new reader we have some tools here to help us make the decision. One valuable one is the matrix
https://wiki.mobileread.com/wiki/E-book_Reader_Matrix . Others have written good comments in this section.
Is it possible to create a definitive rating system? Can we establish selection criteria and assign points to each so we can calculate a rating for each device? Here is a first stab at such an approach.
Cost, screen size, battery life and weight are obvious criteria.
Expansion capability via SD cards would be another, as would be USB 2.0 vs 1.1. Included here would be the ability to put new material on the SD card using a card reader so the PC software for the reader would not be needed. Seeing the card as an external USB drive to the PC is a big plus as is the ability to use high-capacity cards.
Would we consider audio capability important enough to consider in our rating system, or is it just a frill?
Screen type. Some people love e-ink while others like backlighting so they can read at night. How should we consider this?
Availability is a consideration. I would not rate Kindle very highly at this writing, but that will change, I hope. Availability of content is crucial. I would like to be able to buy the newest ebooks as well has having access to all of the classics and technical manuals I already have.
Much has been said about reliability in these pages. How can we quantify this?
Ease of use is another consideration. Maybe we could do a poll on this.
Does the reader include a basic feature set such as bookmarking, page rotation, wireless connectivity, ease of holding, outdoor readability, user maintainability (e.g. battery replacement), openness vs DRMness and competition among available ebook vendors, fonts.
Format compatibility is a big issue. I think a good reader would host many file types natively, but that is only my opinion. The two most common ebook formats for technical books are PDF and HTML. Legacy ebooks for the Palm are often in PDB format. The Microsoft Reader format (LIT) is also common, as is TXT. Microsoft Word compatibility is also useful (DOC, RTF). Some people would find image display capability (JPG) important. How can we assign a value to file compatibility? Is it enough that the PC or Mac software does the conversion? Or should the device do the conversion? How many formats are enough? Are good authoring tools avalable? Are the ebooks you buy for the device usable on another device?
Are there more criteria to consider? Is there a convenient way to calculate a score? Can we generate a poll for issues such as reliability and ergonomics? Can we identify factors which should be subjective considerations vs absolute criteria?
These issues are complicated for the buyer to contemplate. Is there a mathematical method we could use to pare the decision down to one of simply evaluating the subjective criteria and using a rating system for the rest of the puschase decision? This is perhaps an opportunity to give the ebook designers a way to evaluate their new designs.