I have posted this review of my HRM before, so I just copied/pasted it from a different thread:
Polar FT60F Black Fitness Heart Rate Monitor
I have had this since Christmas 2011 (gift from my bf that I requested) and have used it for all of my workouts since then! When you first set it up, you do a little conditioning test (have it on while laying down and staying relaxed for 3-5 minutes so it can test your resting heart rate/condition and estimate your VO2max) and then enter your stats - height, weight, age - so that it can calculate your calories burned. It keeps a fitness log of my workouts and tells me how many minutes I spent in each heart rate zone. At the end of my workout, it gives me a breakdown of my calories burned, heart rate zones, my max. heart rate, and my average heart rate.
You can set up weekly training goals (based on time, heart rate, calories, etc.) and it will give you feedback on your workout habits (I haven't used that feature yet) and you can choose to "lock in" a certain heart rate zone (1,2,3) for your workout and it has a little alarm that will go off if you go out of your target heart rate zone (either above it or below).
It has a chest strap (which is super comfortable and I hardly even notice it once it's on) and a wrist watch, so I think it keeps a very accurate heartrate - and the built in HRM on machines at most gyms will pick up the signal from the chest strap so you don't have to look at your watch while you're on the bike/treadmill/elliptical - added bonus..
It also has a HeartTouch function - when you bring the watch close to the chest strap it will beep once and show you the time briefly so you can easily see the time without going through menus.
Someone who is busier than you is working out right now.
There will come a day when you can no longer do this. Today is not that day.