Very lengthy. The overall process was three months and the most disappointing part was the way they handled delivering the final decision.
I was a top candidate and successfully made it through all four steps of the process. By the time a final decision was made, they didn't even have the decency or courtesy to provide me with an explanation as to why I wasn't chosen. Instead, they sent me a cookie cutter e-mail letting me know they've chosen another candidate that more closely fits their needs.
The interview process should be an opportunity to learn and grow. If you're likeable enough to pass all key milestones, be courteous and provide that person with candid feedback. It's really not asking for much.