Seeing how users browse your site is eye opening. People might say one thing about the site, but they may actually be doing something else entirely. A lot of browsing decisions happen at a sub-conscious levels, so seeing people actually browse your site rather than asking them questions about it is the only way of getting an accurate picture of what people are doing and what parts of the site are confusing to them.
Worth a look, although the userfly js file seems to clash with some versions of jQuery, so make sure your site still works after including it.
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