The main issue (as brought out by Daniel and others) is reviewers, journalists, the techy public are actively LOOKING for reasons to say that the SP3 will not work in your lap. Or using pretty stretched reasons or ways to use a SP3 in their lap (as if they use a laptop the same way). This device is clearly in a new category, one that needs to be viewed in that light and not in combination with the best laptop and then the best tablet.
The reason being is that there will ALWAYS be some type of compromise with a device of this nature. I used this example before (in a forum post), but the automotive industry is packed with quote on quote, compromises. Car manufacturers are building sport-oriented SUVs, wagons, Hybrid vehicles, Diesels, etc etc. All of these choices are excellent in their respective genre's, but start adding in or comparing them to vehicle types that have a singular task and they lack in that department. I mention the Auto Industry because they have a better grasp on reviewing and giving opinions on different types of products and judging them squarely on the market they are after and their category. For instance, drive an Ariel Atom (an exhilarating experience) and you'll quickly love the speed and performance it offers. However, start comparing it to other sports cars and not its niche, open-air concept, sports category and you'll quickly dismiss it as a failure. For example, you'll quickly notice the lack of a windshield. Cup holders? Negative. ABS? That's funny. Cruise Control? Never. Navigation? In your dreams. Heated Seats? Lol. Compare that vehicle to another good performing sports coupe, say a BMW M3 or AMG C63 and you'll notice all creature comforts available. Should I then grant the Ariel Atom a bad score because other vehicles exist that serve better to entertain or comfort the passengers and I? The point of such a vehicle is for the experience, to combine to raw sensation of something closer to a super/sports bike, in something you drive. Based on that idea, you'll read glowing praise about the vehicle. Also, it'll end up costing much more than comparable or other sports cars.
The SP3 is solely in a new category. Something that needs to be judged on those merits. Saying, "..its good, but my iPad Air is lighter as a tablet.." makes it look like you have really no reason to be reviewing the product. Because going in, even on the initial revealing you KNEW it was going to be heavier than any other tablet. I mean seriously, it's 12 inches big, weighs 1.76 grams, the stats alone will show that your about to pick about a pound more in weight when compared to the most popular of tablets. Same holds true for the direct comparison to an Ultrabook. By design everyone knows that a laptop will always offer a better "on lap" experience. That is if you're strictly using in on you lap in the conventional sense, not laying on your back with your legs bent (then it wouldn't be better).
So, you know all of this going in, you see the SP3, you can tell its designed with the idea of replacing TWO devices in one shot. It'll bridge the gap and come as close as anyone has ever gotten to having one singular device. With that it'll have its own compromises. Carrying a better, more "lapable" laptop and a lighter tablet, means you now are carrying a lot more weight, have to charge two devices and need room for them.
In the end, its all about choices and I am appreciative that MS (amongst many naysayers) is continuing down this path with the Surface. I hope they continue and do not fold to creating yet another laptop/ultrabook. If the CEO is honest on creating new categories, we are in for some exciting times.