I think it works really well, and once I saw how it worked, I really like it too. If all you want are estimate calculations in less complex returns, Drake has an adjustment screen that will allow adjustments to the current income for purposes of calculating the next year's estimates. It will then carry those figures over to the worksheet from the 1040-ES package. If you do nothing else and are satisfied with those figures, it will try to use the safe harbor and does take into account the 110% requirement for those with current year AGI over $150K. As a default, it will produce the estimates based on these calculations if no other input is made on the ES screen. You still have the ability to change the estimates to any figures you want. I don't usually use this as I find it easier and get something more to my liking for printouts with the other method.
For more comprehensive planning and the method I mostly use even for just the next year's estimates: Finish a return and with it open, click on the "tax planner" icon and select the current return. You'll understand this once you are using the program and see the screen that appears. The program gives you the choice of another current year scenario or the next year's projection, in this case would be either 2016 or 2017, and you name the scenario. It is possible to have many different ones that you can choose 2 to compare later on in a simple one-page format, or print (hard copy or pdf) of selected pages or an entire planning return with a "tax planner" watermark across each page.
Basically, with this second method, for the first projection it replicates the file and input screens from the current year's original return with all of the data pre-filled that allows you to change any of the input in the new scenario. With additional scenarios from within the planner section, the program allows you to choose which scenario to replicate as a starting point. As Catherine said, once that file is replicated, any changes to the file used as a starting point do not carry over to the replicated one.
For my clients that I calculate estimates each quarter, I start with the original and replicate for the next year's 1st quarter as a starting point and make my adjustments to that. With each subsequent quarter, I start with the one immediately preceding it and don't go back to the original file each time. It isn't much different than the way ATX allows creation of duplicate files that are renamed and would appear in the return manager except that all the named scenarios are within the one client file and then accessed by clicking on the tax planner icon to see the list of planning scenarios for that particular client.