You're not going to get a 10 inch e-reader for $150, let alone one with annotation capabilities. The comparison you could make is netbook + Kindle DX, which is going to run you at least $750 and you still don't have annotation and the two screens don't work together at all...you have to shuttle stuff back and forth on a USB stick or something.

Now, I think Kindle DX is a better pure e-reader than the Edge's eink half, and a netbook is obviously much more powerful than the LCD half. So people looking for one or the other should look elsewhere, but for people who need both and need annotation capabilities it's a good deal.