So for a quick calculation, the basic rate for 2 adults if you weren't in work is £498. The amount you would get for 2 children is £509, and our rent is £675 which they pay all of, even though Local Housing allowance is only £498. You're immediately better off just through that alone. That adds up to a total of £1682. That is what we would get if neither of us worked. Considering we'd have to pay rent and council tax plus all bills out of that, it isn't great. But once you're working, it gets better.
DH takes home £2250 (after all deductions including pension) the first £198 is disregarded so £2052 is the figure they'll use. They take 63p for every £ you earn over that disregarded amount. To work that out you need to do a bit of maths but it's fairly straightforward.
0.63x2052 = £1292.76
They then subtract that from the original figure at the top so
1682-1292=£390
So on top of DH wages, we get £390 UC every month. That will go up in April as the disregarded amount increases.
I started a new job last month so that figure has gone down, I only work one day a week and take home about 410, but we're still getting about 140 UC. You will always be better off in work on UC, and once it's sorted out, it's so much easier than tax credits. You don't have to report your income because hmrc do it. And if you earn different amounts every month, that's fine. You don't have to keep calling to report changes.
I do understand why everyone is so stressy about it. DH and I were a 'test case', we were transferred long before it was officially rolled out in our area and it was horrendous. Nobody knew what they were doing, our claim took 8 weeks to process and we fell into serious rent arrears. DH had been made redundant a while back and when all his reduncany money had been spent (on living and rent!) we had to claim. And looking back, I'm glad we did.
We also, because we were transferred to early, have the very rare 'transitional protection' which means both DCs are still eligible for free school meals until they leave year 11. And although we don't currently use them, it means their schools are still getting pupil premium for them, which is a good thing. And I know that if something were to happen, and one of us lost their job, that transitional protection is still in place. Sadly, that doesn't apply to new claims.
So TL:DR is this. If you're out of work, UC probably isn't going to be any better for you, but for the average 2 parent, 2 child family in work like us, it's great. Which makes a change, because so far every other tory policy has been designed to fuck us over.
We are Theresa's proverbial JAMs!