Why/what is so great about this Developer? Is it for both developing film a swell as printmaking?
It lasts practically for ever. It is very easy to use. It produces great looking negatives for many (but not all) films. It is very easy to make, and very cheap compared to other home brews.
Yes, it can also be used for paper, at about 1:25, and must be made up fresh for every print run. It is easily enhanced by addition of ascorbate, but I would then still use it only for one day's printing. I think it might last longer if one adds additional sulphite, as in 50g/L sodium sulphite, and if one adds ascorbate it might help to add salicylic acid too. But those are guesses. For me, it is so cheap that I simply use once and discard after.
One can make a decent film developer out of Rodinal combined with Caffenol - more info on this on the Caffenol blog.
If you want to make your own using paracetamol (aka acetaminophen), then use the calculator I give in this thread: (there was a url link here which no longer exists)
Others and I have tried it in all possible permutations and combinations, and it works for all of them. In addition to being cheap, it is then not necessary to mix wet chemicals until you need it, and it can be made to any batch size and used within reasonable time frame. I have stored full and half-full bottles of this for a year or more, and haven't seen degradation. To give an indication of cost, it works out to about 5 EURO cents for every 35mm/120 film developed, which is about 10 ml of concentrate (500 ml @ 1:50). By comparison, caffenol and D76 are much much more expensive. Paracetamol as commodity chemical is about 10EU/kg. If you buy capsules, you will pay many times that, and get impurities such as nano-silica which is used to improve the flow properties.