Short version: It's an expansion of Medicaid, with some doodles in the margin.
Today, the US has the world's highest medical spending and poor-to-mediocre health outcomes. It's the only rich country where health coverage is provided by private insurers; where most people's coverage is linked to their jobs; with a large number of people without health insurance; where millions of people lack any health coverage; and where medical problems often mean financial catastrophe. When this legislation is fully phased in, by 2016 or so ... it still will be.
We know what the bill won't do: fundamentally change the structure of health coverage and finance. But what will it do? My own bottom line is, Enough to be worth passing.
The bill's provisions break down into half a dozen major categories: (1) new insurance regulations; (2) health insurance exchanges; (3) individual and employer mandates; (4) Medicaid expansion; (5) Medicare (and Medicaid) spending cuts; (6) tax on high-cost insurance policies, plus a bunch of other smaller taxes; and (7) a grab bag of experimental measures to improve the efficiency and quality of health care. And then there's the provision that's not there, (8), the public option. There are serious questions about the logic and impact of most of these provisions, many of which I have not seen analyzed seriously. As time and inclination permits, I'll dig more into the most glaring ones. The bottom line, per the CBO, is that the uninsured would fall from 19 percent of the population today to 8 percent after 2015. 
I was thinking of walking through the major provisions of the bill one by one. But you can find that elsewhere. (Start here.) I might come back and write up a full summary, but in the meantime, I want to flag a half dozen important issues and questions that I haven't seen discussed much elsewhere.
1. The individual mandate -- is it really necessary to make community rating and related regulations work?
2. the distribution of new Medicaid spending, which is highly unequal between states.
3. The cuts in DSH payments, which could be catastrophic for some urban hospitals.
4. The crazy-quilt employer mandate.
5. Why the public option mattered.
6. How meaningful in practice are the limits on out-of-pocket costs, premiums, and medical loss ratios?
7. How much do insurance companies gain?
There are a couple other issues that have gotten a bit more discussion, where I don't think I have anything much to add.
First, what is the role of insurance companies under this system? It seems they no longer have access to the two main choice variables on which they maximize profits currently: the terms on which they offer coverage, and the mix of benefits they will pay for. If they must offer policies on publicly-fixed terms with a publicly-set package of benefits, there's no margin left for them to operate on. (Which doesn't mean they won't be profitable, just that their profit will depend on federal policy, not on factors under their direct control.) Two possibilities here: First, they will find ways to continue selecting healthier populations and limiting payments; the medical loss ratio restrictions won't bind; in short, the status quo. Second, the insurance companies become essentially vestigial, simply taking a cut off the top of what is basically a public system. Purely parasitic insurance isn't something anyone would propose, but it does have to be admitted it's an improvement on insurance companies that take their cut and try to increase it by denying people health coverage.
Anyway, this is looking at the bill through the lens of universal reform -- what is the logic of the system it creates? Whereas it plainly isn't fundamental reform, and it doesn't create a system with any particular logic, just tweaks the system that's formed itself willy-nilly.
Second, the abortion restrictions. It's clear that for some women, the bill will actually make things worse -- it will restrict abortion coverage compared with the status quo. How much, for how many? I don't know. But I did want to flag this lovely quote from The New Republic: "Poor people pay surprising amounts for cell phones and cable TV. They can be surprisingly resourceful in paying for abortions, too."
 Also, at The New Republic, Jonathan Cohn writes, "For nearly a hundred years, the political system has been debating whether access to basic medical care should be a right all citizens enjoy. When reform passes, the political system will finally render its verdict: 'yes.'" But 92% -- or even 94%, if you don't count undocumented immigrants -- is not "all". This kind of dishonest rhetoric has been all too common among those defending the bill.