Guess I'll start off with API. It's definitely the cheapest @ ~$9-$15 depending on where you find it. Which is another plus for these. You can find API just about anywhere. I picked this one up and my LFS.
The biggest con for this kit is that it's not designed for ultra low ranges. Which for me is OK. I'm just looking to be bellow 5 and that's easy to see the difference between 0 and 5 on the color chart. At least for me it is.
Testing wise its also not the easiest as bottle two you really really really really really have to shake the snot out of it.
One other note brought up before is the accuracy of the vial. Well, its not accurate. Or at least I've never depended on it. I draw 5ml out with a syringe but it seems to line up pretty close when I've thought to look.
As for the results, they are just as I've always gotten.
I read that as undetectable or according to API as 0. In fact I don't ever remember having a nitrate problem. I've had plenty of PO4 problems and mainly from pukani dry rock leaching like mad for over a year before it was known that they do that. Only if I knew then what I knew now and lanthanum chloride would have been extremely helpful. But carbon dosing did wonders for me and I learned a lot.