This is a non story really. Essentially, the changes are that you no longer get a paper tax disc. You get the option of paying by direct debit if you wish, and instead of selling a car with tax you now have to claim it back at the time of sale (something which I always do anyway).
So, you don't have a tax disc any more, but you still get the reminder through the post. Not really a big change there.
So, you get the option to pay by direct debit, but you can still pay yearly if you wish. Nothing changed there other than a new payment option has been added for the drivers convenience.
So, you get a refund of the tax back when you sell a car, and tax the new one when you buy it. That's no big difference really except for the people who like to give away a few months tax on a car they're selling. Personally, why would you want to do that? Cash it in and have the money in your pocket to pay the tax on your new car. The mechanics of cashing it in and new owner re-taxing it hasn't changed. Only full months tax can be claimed back just the same as before, and if you're taxing a car then you have to tax it from the start of the month. The benefit for the Government (and in reality for all of the road users) is that from now on all cars must be taxed, MOT'd and insured at point of sale, rather than people driving off in a car with some tax on the screen and feck all else. If they're not insured / MOT'd then they won't be able to tax it.
There's no more data being gathered, compiled, or held by DVLA than there was under the outgoing system, so no change there.