Not too sweet or messy - just right
If you've never used these before, they take a bit of getting used to as they are not like your ordinary powder mix. Instead, they are tablets roughly the size of a quarter (half dollar?) which you plop into water and they then dissolve by fizzing. Depending on how strong you mix it, Nuun creates a very light flavored sports drink which is very palatable for long distance events, like a full day of backcountry skiing.
As an added bonus, they come in a small plastic tube, which if perfect for travel and/or storage. Unlike a bag or tin of sticky powder, the Nuun packages won't spill all over everything and gunk up your junk.
I'll often use just half a tablet, which is easy to do as they come pre-scored for easy breaking in two.
They got a 4 instead of a 5 due to being so pricey.