Strengths: Reasonably compact compared to some GPS models. Can be used in cities, woods and indoors without losing monitoring ability. Quality construction. Very accurate even without calibration. Plenty of timers and interval training aids. Can be purchased for £140 these days! Great software to help with post workout analysis
Weaknesses: Theres a large manual to digest - this is a complicated bit of kit. Can never be as purely accurate as a GPS based system. Foot pod expensive to replace.
Overall: A fantastic product which enables you to accurately measure speed and distance for running or cycling. Not prone to the same inherent weaknesses as GPS systems (i.e. not brilliant in built up areas). Great value now they can be bought for around £140.