Great shirt.  Ive had intelliskin shirts in the past and the quality is comparable.  I ordered a small in this shirt but probably would have been fine ordering a medium as well since the chest is a little snug.  Im a 32DD size 2 and its not painful but the support is similar to a high impact sports bra at this size.

Im a pretty straightforward medium in intelliskin shirts so this one is slightly larger.

This is helping my back and shoulders and Im happy I purchased.  Youre meant to feel a bit of a tug for it to be working - so I think some reviewers may have benefitted from ordering a smaller size if they are complaining it was loose.