Strengths: Great training assistant, good for assessing and setting your pace and distance for both running and cycling. Great intervals feature for speedwork. History feature helps to track progress over time.
Weaknesses: Can be tricky to track a satelite in built up or wooded areas. Mine has been known to switch itself off for no reason and has told me I'm doing 12 min miles when I know I'm going faster. Battery life not great.
Overall: A good tool for the both the beginner and the seasoned runner. Helpful in guaging distances and helping to set and keep to pace. Can be tempremental in certain areas.