The tool has helped us monitor our website's traffic flow better than ever before! It provides all kinds of useful metrics regarding how many users use what pages etc., which helps me understand my audience more effectively (which in turn gives you an edge over your competitors).
I don't think there are any downsides as such; however we would like it if some other functions could be improved or added into future versions - ecommerce analytics/e-business intelligence being one example among them that comes immediately at mind.. However this should just take time because these things need resources & knowledge about implementing features from scratch ;) Great product overall though with great support team behind its development too :) We have been able using articon proxy tools since 3 years now so i cannot recall anything negative yet but then also not much positive either! So far everything looks good :) There was no downtime when switching servers last year due weather related issues :P.