Haven't done it but have considered it and recently found out that some folks in my regular ride group have made the gold cutoff in previous years. Don't think any of them have done it more than once so seems like a ride to check off your list rather than an event to look forward to riding yearly.
The challenging part is actually the first half to the top where it's timed. Then it's mostly downhill back to the start.
I don't like that it's on a weekday necessitating either a long and early drive from Seattle or lodging arrangements.