Strengths: Large display that those of us with less-than-perfect-vision can actually read. Comprehensive PC software utility. Web-based software sorts out the altitude accuracy from map-based altitudes.
Weaknesses: Crap strap that has to be thermo-formed to get it to sit properly on your wrist. Poor Heart Rate accuracy going slowly up hills on default 'smart' capture setting. Terrible cumulative altitude gain accuracy - it can be three times too high !
Overall: I wouldnt be without it now, but you mustnt treat all its data as perfect !