The unofficial medical consensus is that on average ecigs are appr. 75% "less harmful" than cigarettes.
That was before the recent FDA approval as a cessation aid, so the official medical standing may have changed.
Note that it is not 100% healthy for you...as almost every breath you take anywhere is not pure air or healthy either.

I have never heard of a person being able to smell the vapor from a non flavored e cig.
We did a "field test" with a friend of mine who is the classic anti smoking crusader.
This guy chokes if a person even THINKS of lighting a cig.
I blew it directly into his face from inches away and he smelled nothing.
The flavored ones I am pretty sure do give off an aroma though.