Comfortable. That is very much the first thing that comes to mind. Perhaps it is the sizing, where the medium could be a little tighter but honestly probably wouldn’t do much more binding, otherwise it is just the structure of the tank.
My binding regime is now streamlined from a frog bra, elastic band with safety pin, and gc2 tank to just the 997. This has 2 huge benefits- I can get dressed a lot faster than before and I’m not getting hot inside as often.
The tank is double-layered in the front and single in the back, very streamlining. The armholes are cut fairly high, but they’re not uncomfortable for my wide shoulders. Even at 5 foot, I’m a big boy- I was probably ~C to D chest.
For sure worth the $30, and Underworks’ exchange policy is excellent for sizing issues.
Two pics, for comparison (and to brag):
Edit, to update for the year I ended up wearing binders before top surgery:
The Underworks 997 remained my binder of choice, but as my body changed on testosterone I ended up wearing 2 binders at a time for best appearance. Every few days I would hand wash the 2 binders at night before bed, leaving them to air dry overnight. Ace bandages and back braces caused me a lot of trouble for binding, so I can’t emphasize enough how helpful the underworks 997 was. They’re not always as available, so don’t be afraid to shake up your regional trans* network to see if anyone has extra binders following surgery. (All 3 of mine found new homes within 1 month of surgery)
Oddball Orbital Transformation: FTM 
I realize this post is old, but I found it while googling the underworks 997 style binder and I was hoping you could tell me more about it.
I’m glad I’ve found someone who is the same height as I am (even same bust size too), because I’m concerned about the length. I haven’t purchased one yet because I want to make sure it’s the right chest binder for me.
So have you had any problems with the length? Rolling up or reaching down to your thighs or anything?
I’ve also read some other reviews that said the fabric is uncomfortable. What is your opinion on that?
Also, your chest looks very good in those pictures. They almost have me completely sold.
I’m so sorry about the delay- I hope that you found that the 997 is plenty long, I tucked it into my pants and it stayed in place really well.