I just bought the Polar CS300 heart rate monitor. I purchased it with the idea that it would make a decent cycling computer and I could use it for various other sports. The unit is simple to use and I'm imagine most people could get by without ever reading the manual. Some of the stuff like own zone and the fit test stuff are specific to Polar so it helps to read about those functions.

What I like:
-easy to use
-not that big
-easy bike install
-seems pretty sturdy
-easy to read screen
-buttons have a solid feel for easy key presses
-Large variety of screen displays
-compatible with other computer programs for data uploads
-can be used off the bike for most other sports

What I dislike:
-I've had some trouble with the Sonic Link system, I've contacted Polar and asked about it..
-It would be nice to be able to customize a few screens to show information I want and not be stuck with the predefined screens.
-I tried swimming with it. Chest strap won't stay in place, if it does it will pick up the heart rate.. but how do I keep it in place?!
-The cadence sensor sticks out off the down tube more than I like but I'll get used to it.

Overall I'm really happy with it. It's certainly not a super high end 101 feature monster HRM but it's damn nice for the price. I have nothing else to compare it to so take what I'm saying from the perspective of a first time HRM owner.