I bought one and returned it yesterday. The screen isn't that much sharper than a Kindle, I thought, especially with the bold Kindle fonts. The dealbreaker for me, though, was the page turn lever in the middle of the device. It's loud and takes too much effort to press, compared to the Kindle's and the easy tap on the touchscreen readers. It just seems obsolete to me, especially compared to all the new devices coming out, especially the new Kindles. I got a K4 non-touch yesterday, and it's smaller and lighter than the iriver, and the page-turn levers on each side are small but easy to use and almost silent, so I'm not distracted by them, as on the iriver.
Also, I was hassled a little by the Target customer service person, saying they don't accept returns on an opened device, but then they had someone from electronics look it over and approved it, but it wasn't a pleasant experience, so be careful if you get an irriver and hope to return it if it doesn't work out.