Real good in fact! - I've been taking it for over than 2 years.
Sometimes I take less, when I feel I don't need it. When I feel a cold coming up, I take double/triple doses for 3 days, and it just doesn't come through (before, a tickle in my throat would certainly predict a heavy cold). Strange, but experienced it over and over again.
It's standard in my Dr's protocol.
Also: my stomach doesn't accept much, acid like supplements like Vit C in tablet form are very uncomfortable for me, this is a very good solution.
The taste isn't great, and stirring it isn't good, it breaks the liposomes. I put water in a glass first (otherwise the gel sticks to the glass), squeeze it in the glass and drink it without stiring or trying to get it dissolved in the water.