Initially tried without adjusting straps and was unable to get anywhere near fastening.
Managed to get on after fastening and 'wriggling' over head with lots of squeezing, shaking and shoving!
After adjusting strap managed to fasten fairly easy, however struggled with the second fastener and had to get hubby to fasten for me, although I did forget last time and left it unfastened and it was fine.
It does offer very good support though and I'm sure it will loosen off slightly to allow easier fastening.
Rated 4 because of fit - even though I do always go up a back size with sports bras - that being said my general rule of thumb is whether or not I would buy again and in this case I would.