Low calorie, natural taste. I can drink this all day in any condition (hot, cold, etc) for a short ride or greater than a century. Most drink mixes bother my stomach or I just get sick of drinking them after 5 hours in the saddle. Nuun goes down easy and keeps me hydrated
I have tried a lot of drink mixes and prefer EFS because has some sweetness, but is not too sweet and has the taste. It does the job of providing hydration and energy on a hot summer day of biking or a cold winter day of XC Skiing.