In all honesty the healthiest shake I've found is from the healthy mummy. I compared all the damned products and this was the highest protein, lowest sugar etc etc. I did try optifast but it had more sugar, less protein etc etc.
I used it for a month, kind of get used to the taste eventually.
Weight wise it did not assist me (also exercised in conjunction with it)
As for feeling full - full for maybe a halfa after having it than starving.
Those were all the negatives but the positives were-
A) WAYYYYY less sugar than all the other diet shakes
B) More nutrients and actual good stuff than other brands