The 10" slate is great for reading a lot of content, although it is a bit small for the layout of some sites. Book reading ala iBooks, Kindle and Nook apps, Stanza and other apps is good, but the backlit LCD does tend to cause some eye fatigue over long periods for some people. Also, due to the massive battery, the wieght can be somewhat of an issue and make it awkward to hold for long.
Battery life is estimated at around 10 hours, and is fairly accurate. Even for heavy users, you can go all day without charging. For most users, you could probably get by only plugging in every 2-3 days. 5 stars here.
Flash is the main issue here. While many website and services have converted to HTML 5 (due mostly to Apple deivices), not all have. You will find that many websites you visit won't display properly, or you can't see the video. In my opinion, this is a big deal. For many, this is a web consumption device. If you can't use even 10% of the web, it's still a huge nuisance. I find a small, but important percentage of the sites that I use regularly are either hindered or downright unusable on the iPad.
Java, and Apple's recent change in support for it may cause some heartache in the future - a lot of this will come down to developers and if they are willing to change the way the produce apps. I beleive that Apple actually changed their submission terms such that apps using Java will be rejected. We'll see what happens on this one.
On a high note - publication compatibility is awesome. With numerous reader applications like Kindle, Nook, and Stanza for books, you can read pretty much anything that is published digitally. Comic books are experiencing new life and finding new readership with apps like Comixology, and the DC and Marvel readers (although the publishers seem to be a bit slow on ramping up the amount of available new content so far.)
Apples build quality and fit and finish are typically top-notch, and the iPad is no exception. The aluminum back and glass touch surface are beautiful and perform like you would hope. Due to using glass touch surfaces instead of plastic like some resistive touch screen devices, scratches are pretty uncommon.
As with most other Apple devices, the screen is nice. Not jaw dropping, but acceptable for a $500 device (for the 16GB wifi only version anyway.) The glossy LCD is almost impossible to read in sunlight of any kind, so it's pretty much and indoor toy. I'll keep my Kindle for real reading. Pixel density is a little on the low side in my opinion, but most people don't seem to notice. I got an iPhone 4 this year and I notice the difference. Maybe the new model will have Apple's Retina Display. I think it's because I tend to hold it a little closer than my PC monitor would normally be.
Typing on this thing is an exercise in frustration. It's no worse than the iPhone keyboard, in fact with the larger size and hence keyboard, it's a little faster. That being said, there are just a lot of problems here. You don't expect to type 50 wpm on a phone, but people talk about the iPad as being a netbook or notebook replacement. Not going to happen. It's a little to big to use your thumbs as you would on a phone, and you have to lay it on flat surface to attempt to touch-type. In addition to that, the keyboard layout is a little non-standard and some characters are hard to find - good luck finding the "#" symbol in a hurry.
Angry Birds, Plants and Zombies, and We Rule. From what I read on the internet, that's all anyone plays anyway. There are over 200,000 apps in the App Store. You can get anything you want, if not, jailbreak and get access to a few more. There are some apps that just make more sense on the iPad over a phone because of the amount of screen real estate. You won't find as many free apps specifically for this device as compared to the iPhone, and paid for apps are typically more expensive for a reason I still can't figure out.
Non-existant at the moment, but supposed to be addressed in iOS 4 due out next month. For now, face-down on a copier is your best option.
The worth of this device completly depends on what you use it for. I can't see myself getting any "real work" done on it, but it I definitly find it satisfying to sit on the couch and catch up on my favorite blogs or stream some netflix on it. Games are great and plentiful and many hours and days can be lost in the heat of battle, working puzzles, or your favorite Scrabble clone. It's nice to read email on, but I cringe when I think about trying to send more than a two sentance reply. All in all it's a nice device. It can't replace a real computer at this point, but it's obvious that Apple was able to wildly succeed with a product in a niche that Microsoft has been trying to create for close to 10 years.