I gave it a whirl once. Still have a big bag of it, must be at least 10 years old.
It's very high sudsing, as I recall, but has STPP init. At least my 10 year old bag does.
As for the dosage, it's not an ultra, probably has plenty of sodium sulfate filler init. This is not a big deal; more of a concern is the high sudsing vs. HE washers.
If you use a traditional top loader, you may be pleased with its performance. If it still has phosphates, that is.