I've had my datalogger for three years now and still enjoy it. It has it's quirks, as the other reviewer pointed out, but it's not very expensive unit and I definitely feel I've gotten my money's worth.I've never had it fall off or cut out during a session.
The software isn't very modern, but it does the job just fine. I like the graphs and how it shows the time spent in each heart rate zone. The data exportable in csv format if you want get fancy with it elsewhere.
It does show some erroneous beats one in a while (240bpm range), but they are so few that it doesn't skew the stats.
I wear this data logger jogging, cycling, and also motorcycle racing. I've also had it on for a whole day at the office just to see what it looks like.