I'll toss out my own experiences with my eDGe - I bought one last time they were here.
Hardware-wise, this is a decently, but not fantastically, capable little device - the dual screens are the most obvious feature, but it also has WiFi, Bluetooth, USB host capability (the ability to plug in a flash drive and copy files is, IMO, a very underrated one), and a microSD slot for expandability. The processor is a Marvell something-or-other, and it's ARMv6 instead of the more modern ARMv7 - the biggest side effect of this is no Firefox. (Shame, really, it would work well on that big screen. Try Dolphin or Opera instead.)
It comes with what is, as best I can tell, 4GB of internal flash, of which only ~1GB is partitioned out as internal storage, leaving the other 3GB as a sort of pseudo-external storage which appears as the default SD card under Android (the one mounted under /mnt/sdcard). Why they didn't just make a bigger /data partition is beyond me... In any event, though, you're unlikely to run out of storage for your books and such. Music is something else entirely, but fortunately the media scanner seems capable of picking up media stored anywhere (internal storage, external SD, or USB).
Other complaints include the fact that the screen is resistive-touch, meaning *no multitouch* - this threw all the muscle-memory gestures I had from working with other Android devices until I adapted. On the other hand, the stylus support on the e-ink screen is quite useful, and, as far as I have seen, unique among e-readers.
As far as software is concerned, out of the box, it's not fantastic - Android 1.6, no Google apps or market support, kinda buggy. That said...
Upgrading to Android 2.2 is dirt simple - log in on the Entourage site, and it gives you the option to upgrade. Not sure if it's that easy anymore, but I know someone mirrored the update.zip that's necessary to run the upgrade. Google about for it if you need it.
Rooting the device from that point is remarkably easy - download z4root from Amazon Appstore. Push the "Root Device" button. Done.
That still doesn't get you Google apps support, but if you have another (also rooted) Android device, it's entirely possible to use Titanium Backup to copy the apps over and get them installed - instructions here. Market support can also be added with a similar hack.
I successfully copied over the Google apps packages from my Epic 4G, and now have working Market, Gmail, Talk, YouTube, and Voice, complete with background data sync. The background sync seems kinda flaky, though - I often have to manually refresh. Still beats nothing, however. (For those of you who don't want to follow these hacky directions to get Market running, Amazon Appstore works just fine.)
As far as useful packages to install - Swype is available as a public beta and is incredibly usable, especially with the stylus, and SwiftKey is also lovely ($2 in the Amazon Appstore). Angry Birds runs, but has some coloring issues (blue and red are swapped). Some apps work well with the larger screen, some don't. Give things a try, but be prepared for unusual displays or outright breakage.
Bottom line - if you just want something that "just works" out of the box - buy an iPad. If you're willing to put a bit of effort into making this thing run, you'll be rewarded with an awesome device at an awesome price.
Edit: Broke up the wall of text a bit.