Not comparable to ipad
The advantages eBooks have over the iPad in terms of longevity are ridiculous--measured in weeks, not hours.... They are also much easier on the eyes and viewable in more conditions. So for the price of an e-ink device, which is *usually* less than an iPad, I'd say there is a niche.
This device justifies its iPad-like price, on the other hand, by adding something the iPad *doesn't* have--stylus input. This is really something where there is no contest with the iPad--if you want to not only read, but also annotate stuff and take notes, there is no contest--this is the better device.
The main thing the iPad has over this device for the foreseen use cases (reading and taking notes) is the ability to present the internet in all its scrollable, messy glory. On the other hand, the scrollable, dynamic nature would be a challenge to integrate with annotation anyway, so in that sense it's not a huge loss...