having used the Breath for a few sessions now, i'll throw in my first impressions.
like Dimitris i got a size 6, but i weight a little less at around 70kg for 178 height.
when i first got the suit, opened it and looked at the size, i had a chuckle "how in the world am i going to get into that ?". seriously, it looks like it belongs to a nine year old boy. with time and patience it goes on without any issues. however, like everyone says, it's TIGHT. and tight it's meant to be. there is of course a boarder between tight and feeling squashed, fortunately the tightness is ok for me.
the first time i put it in the water however, during warmup it did not feel that great as i felt fairly constricted around my chest. my breathing felt restricted and the first contractions felt stronger, as if they had nowhere to go. that worried me a little but i just kept at it to see how things would develop.
after two dives i already felt much better, as if the suit was starting to stretch and take my body shape, and by the end of the session it felt like a perfectly fitting second skin.
the next day, the suit felt really good from the first minute in the water. i guess i got used to the feeling and maybe it actually did start to stretch a little where needed (although i do not see how it could have happened so fast).
like i said it'd tight, not a needle will fit in there, but it's also perfectly fitted and makes you much more "compact".
the feeling in the water is that of being VERY streamlined and hydrodynamic. i really felt "slippery", as if i could glide through the water much better than before.
all in all the experience so far is very positive and i can only see advantages to the suit.
of course, there is no better test than that of time, so lets see how things shape up. so far though, the breath and i have had a very happy (and close...) time together underwater.