This is definitely worth the $25. However, don't expect it to work perfectly. The strap seems to work amazingly for biking, and pretty well for walking. However, I've had mixed luck with running and on my elliptical machine; I don't always seem to get a good signal. Sometimes, it works pretty well with only a few weird readings, but other times it reads either 238, 0, or the last number it received pretty much the entire time. I have the chest strap in the right area and I even adjust it to try possible better positions. I always thoroughly wet the conductive pad of the chest strap before putting it on, and I sweat pretty profusely so it's usually soaking under it when I take it off. Maybe my skin bouncing around excessively while running causes the readings to be less efficient.
I'll address a few things that confused me when I got it. Firstly, the chest strap is REQUIRED to get a heart rate reading. The product info led me to the assumption that you only needed the chest strap for CONTINUOUS monitoring, not intermittent monitoring. The HRM will NOT work without the chest strap.
Secondly, place the chest strap immediately below your mammaries. I have rather large pects due to muscle and fat, and it never worked when I tried to place it directly over my heart. If you place it right below, it works well for the most part. Therefore, the HRM WILL work for females (some of you are confused about that).
Thirdly, a quick way to measure HR is to just go into chrono mode with the strap on. Once you push start, it will continuous record your heart rate and spit out data like calories/fat burned (based on your inputted weight), average/max heart rate, and other stuff. I've never used timer mode. The watch will tell you heart rate without pushing start in chrono mode, but it won't save any information.
As aforementioned, for biking this thing is great. Even on some runs it's invaluable (when it's working properly), as I get a good idea of how hard I'm really working (I need to be about 150 HR, anything over 165 leads to anaerobic respiration it seems). Speed isn't always indicative of how hard you're pushing, particularly if there's wind and stuff.
So, in summary, get it, but don't expect perfection.