The product has been very helpful in tracking down issues with some older ASP.NET web apps I've inherited from previous employers (at least 5 years old).
It's not perfect - sometimes can be difficult if you don't know where your logs are stored/what version etc., so take note! We use this app primarily as troubleshooting tool during normal business hours while using other logging products outside work times would have saved me several days worths trouble trying things out myself at home after office closed each day!!