The interview process spanned over a month and included a preliminary call with the recruiter, followed by a phone screen with the Hiring Manager. Then I met in-person with the VP of Product, after which I was brought onsite for a full round of interviews, which was an all day affair (10am-5pm). It included a presentation + Q&A followed by interviews with 4 PM's, VP of Product, Design, Engineering as well as 1:1 time with one of the co-founders.
Although the interview process felt lengthy, I enjoyed talking to the broader team and learning about the company and the PM culture at Thumbtack. The interviewers were friendly and kept you at ease through the interview process. Most of the interviews were design/case based (which I personally prefer) and some even involved problems that the Thumbtack team is dealing with. Each of the PM interviews focused on an area of competency (e.g. Analytics, Technical Skills, Strategic thinking etc.) and the interviewers would often pivot to test the depth of your thought process.
Although the process took the entire day, it gave me an opportunity to meet with a fairly diverse group and get a good sense of what it's like to be a PM at Thumbtack.