After one day of use I have to say this: I had no idea my blood sugar reacted in this way.
For instance: Yesterday for lunch I went out with a co-worker for her birthday. I got a chicken avocado club sandwich with a side salad. Total carbs guestimated at 40. I bolus, eat, and watch my blood sugar. At first it starts going lower (from 120 to 105) and then, about 45 minutes after eating, it starts to rise. It continues to rise up to 156 at the two hour mark. In my head, if my blood sugar was at 156 two hours after eating I would just assume that it had been even higher for the previous hour or two. In some cases this is true, in others, obviously, it's not. I just had no idea.
One difficulty I'm finding is that while I'm watching my blood sugar rise after eating, it's so HARD to wait the two hours to see what it will end up at. I want to start corrected right away when I see it at 170 or so, even though after the requisite two hours it might well go back down to 120 or 100 even. It's hard not to jump the gun.
While this thing is currently the best of the best, it isn't terribly small. If I tried to wear any form fitting shirt I'd have a very noticeable bump. But, for the next 5 more days, I don't give a shit about that. I can deal with the inconvenience because the benefits are pretty amazing.