I have the sony 300 pocket edition. It is my first eReader, was a mom's day gift this past May.
I ruled out Amazon's Kindle due to not being able to download books from the public library. I wanted portability.
I'm a happy camper. No problems with the Sony software, Adobe digital editions or Overdrive. Right before the new Reader's were announced this summer I was able to snag the dc charger for my Sony for under $9. So now, as long as I have bookmarked, my library book stays on my device until I finish it.
The space available on this device has been plenty. I don't buy ebooks, strictly download from my public library for my entertainment reading fix. So have only had a max of 4 books on it at one time.
The positives: I think Sony's menu system is practical & user friendly. I like where I can see how many books are loaded at a glance, just push the side menu buttons to quickly go where I want. I mention this because we purchased DD a Kobo for her Bday. She loves it, but I don't like the menu system as well as Sony's. Seems you have to scroll thru lots more clutter to get to the book you want to read than what I do w/my Sony.
The screen and text are easy to read, no glare problems in sunlight. Fits in my purse easily. I have the protective leather cover w/book light for it. I've been using the Sony reader software to keep track of the books I have downloaded.
So far, my Sony reader has been very durable. I try to be careful but it does get casually stashed in purses, bookbags & backpacks. The balance w/the protective cover is excellent IMHO. Feels right in my hands.
Would be nice to have a quicker startup time, and quicker page turns but other than that, it does everything I need