Strengths: When working properly, impressive data can be obtained.
Long sampling time allows data to be stored for the whole of you holiday.
Weaknesses: If you're doing a pool based triathlon and you decide to leave the monitor on the bike mount, you have to start the watch BEFORE you get in the pool within range of the hr transmitter or you get no hr data.
Sensor batteries for cadence and speed are expensive and don't last long.
Sensor range can be a problem.
Data manipulation with the poor software tends to spoil the day
Overall: If you manage to operate within the confines/operating spec of the hrm, a lot of useful data can be obtained and if used wisely, will help achieve your goal. This may not, however, be how you train