So your only drinking water for 10 days? You will have to let us know how much weight you lose
Assuming a sedentary lifestyle, you lose at least .25kg a day, closer to .4kg if your a large build, active, or more significantly overweight. Not something I would ever contemplate doing for 10 days, even with complete vitamin and electrolyte supplementation. The body cannot synthesise a number of essential amino acids needed to create proteins which results in a breakdown of muscle tissue.
I found that it tasted innocuous, but I wasn't paying much attention to the taste. It's food as a fuel, not food as a taste. It's likely to taste inoffensive to everyone, but since taste is extremely subjective then the only true test for anyone is to try it.
It doesn't mix easily, so if you want it completely smooth you'll probably want an effective mixer. I didn't care - a quick whisking with a fork and I drank it down with a few lumpy powdery bits in it. I ought to get some more and use it for breakfast. I tend to either not eat breakfast or get something on the way to work and both are bad for me in different ways.
Doesn't sound like something that would work as a meal replacement for me then, especially considering how expensive it is, it costs much more than an actual meal! I would just rather buy a 400cal sandwich which would actually be satisfying.