I've never used it before. Everything it says about "purifying", preventing algae, eliminating nitrates, and having live bacteria seems like a scam to me. The minerals/nutrients provided could be real, but then I feel like the exact elements should be listed somewhere. How one doses depends a lot on the type of plant, growing conditions, light, etc. So just having it based on water volume seems like it would be very hard to dose accurately. If only one element is low, then the plant can get growth defects and not grow as healthy (Allowing algae to move in and take advantage of the extra nutrients as the plants struggle).
For example, if humans have a super healthy diet except they never get vitamin C, they will end up getting sick. While plants don't get scurvy like people, they still need a balance of nutrients.
I'd say, if anything, the kit probably has veryyyyyy tiny amounts of anything useful. I doubt it's harmful, but I don't see it being likely to have any noticeable positive effects. Flourish and excel are probably more reliable, but to really make your plants happy, spot dosing specific fertilizers is the best. I recommend whatever all-in-one liquid fert you find from a reputable brand until you learn more about your new plants growing habits and how to dry fertilize.