I agree that picking up a Kobo WiFi is a better choice ... assuming a price point around $100 or less. I believe all the original Koo's have a "blue" navigation button; the wifi edition has a "grey" button. (The wifi is also slightly heavier.)
I happened to read an entire novel in pdf format recently using the original Kobo and it was awkward but once I got into the rhythm of it, I didn't have any problem. I would always opt for ePub with Kobo if I had a choice.