I find this tool very very useful when you have lots of integration job. If you have an enterprise version, then you can do stuff like compare and merge files across two servers, compare PDFs, ZIPs, JAR, and obviously plain text files. This is a tool for which I definitely ask for an Enterprise Version license whenever I join a new organization.
the ability to compare and merge directories is also nice (although a number of open source diff and merge tools also support this -- e.g. kdiff3, meld)
I simply bought myself a license and use it on both the company and personal machines.
My personal favorite is the Git mergetool integration with gives me a three-way merge (with the common ancestor). This is absolutely indispensable when trying to do complex merging and has saved me countless hours.