I love that it's not just for analytics but also allows me keep track of my visitors in real time - so no more losing those details with cookies! It is very easy to use, although sometimes can be slow loading when lots are being viewed at once or if there has been an error somewhere along the way (no idea why this happens). Nothing really- we've used other methods before like Google Analytics which was too clunky/difficult to navigate properly. Just make sure they have good support available as some questions may take longer than expected to get answered. We're currently looking into how visitorlab will help us monitor our site traffic better over holidays / long weekends etc where normally people don't visit sites as much because their busy during week days.