I got a Flex last February, and still think it's a fabulous investment. I can just strap it on and forget about it, and it helps calculate how much I can eat when synced to MyFitnessPal. There's lots of cool graphs and charts if you're into that stuff, and a place to log different measurements (I log my blood pressure). It also helps motivate me to get up and move more! (especially when my family/friends are kicking my butt at step count)
I used the alarm when we were co-sleeping since it didn't wake her up, but now that she's in her own room I just use the alarm on my phone.