Let's just say that I'm not a 34 DD.  I'm a 34 DDD or G, depending on who measures me and what brand we're talking about.  Naturally.  Anyone that wants this via surgery is nuts.  I went to a local sporting goods store and this was the largest sized high impact sports bra they carried.  I can squish my way into it and once there it does what it's supposed to.  I was a little limited when trying it on so I didn't really get to see just how much impact they considered "high."
I play flat track roller derby.  It's an aggressive, rough, high impact sport.  I also cross train, doing anything from MMA to HIIT.  For the last year or so I've been desperately looking for something that can keep up with me and was wearing out two older Danskin brand bras I got from the local wally world layered with a no-name band bra and topped with some sort of minimizer, cami, or running tank.  All that and I still felt a little... jiggly.
Pros: I do like that I can skip three or more layers under my jersey and rely on this.  It also provides good coverage so I don't need to disappear to the back if I have to switch jerseys during a scrimmage or something.  The should straps are wide enough to not cut but not so wide I can feel them when I lift my arms.  It also provides a little extra material around the sides so no sneaky side-boob.  The under band was what I would expect for this cup size.  It also shows up as a simple black bra with white and some purple detailing, the pictures make it seem like the purple is going to stand out but it doesn't.  Which is a good thing, our team colors do not include purple.
The front is also lined with removable panels, which I didn't realize until I read it on the label.  That's actually awesome, though I'll probably never remove them.  The panels are super thin, they do not provide extra mass (because seriously, once you get to be this big you really don't want to add to it) but they do provide a little modesty after a hard practice followed by a late lunch in a cold restaurant.
Probably the best feature is that this thing has HOOKS.  Adjustable ones.  In the back.  And the straps are adjustable.  That alone makes this beast worth the money.
Overall the bra is well made of good quality materials, it looks nice, and has the features I wanted.
The cons: Well, for one thing... the price.  This thing is almost 60 bucks and there's no way that this is going to last me all season, which I would expect from something at this price point.  Those cheap wally world bras I mentioned are at least five years old.  Yes.  Five years.  This won't live that long while still providing the "high" level of support.  If I hadn't packed it in a hurry this weekend and worn it for almost 16 hours straight I would probably return it.
I did get to wear this for a practice and a game so I got to test out the support.  It was fine, though not super.  I did feel a little jiggly and my neck and shoulders felt sore by the end of the day.  The bottom half holds up well but the top seems a little loose.  That's where most of the unsupported area seemed to be.  Thankfully it held all the bits and pieces in place so there was no spillage or need for panicked adjustment after a hard hit.
The last gripe I have is with the thin plastic buckle thingys on the straps for adjustment.  They're a little uncomfortable and one side refuses to stay in place.  The loops at the bottom of the straps are also a little uncomfortable.  I can feel them digging into my shoulders.  Neither side will keep the straps flat either, and I had to ask a teammate to wiggle them back to flat a few times because it formed a hard knot and hurt.
This runs true to size, more or less.  I would suggest that you really take this thing for a test drive before deciding whether or not to keep it, and pay attention to those plastic strap pieces.  It's okay for support, not amazing which I would gladly fork twice the money over for.  It also fits smoothly and doesn't make a complete uniboob, something that's nice at this size.  Give it a try, you may like it.  I'm just meh about it.