I recently bought an Irex Iliad (firmware 2.8) and I am quite content with the device. Main advantages (to me) are:
- A big screen (larger than the Sony), so easier on the eyes
- 16 colors (vs. 4 for Sony)
- Possibility to make notes on PDF. This is a really nice feature of the Iliad!
- Zoom possibilities makes it easy to read almost every text.
- No conversion needed: The Iliad reads standard PDF and HTML (and several other formats).
- Usability: The Iliad is very easy to operate. I like the flipbar (to flip pages) very much. I can't compare to Sony however.
-Regular updates, with very easy install using WIFI.
- No DRM: I don't want to "hire" content and become dependent to the software supplier or become limited to one device.
For the techies:
- Linux inside so I can adapt the device to my needs if I'd like to. For example I can add a chess program and a calculator. But it is also possible
I now have more than 4 Gb of pdf's ready to be read on my Iliad. In my Iliad I have a MMC card with 1 Gb of books (computer, business, philosophy, life sciences/biology, literature). Great!