Overall when I was in the interview process, at first I did find it very professional and quick until they were hesitant on giving the offer.
For context I was interviewing with them for about four and a half months. Really only the first few interviews took about a month and a half to complete, which was three rounds. There was meant to be a fourth but while they did say "I was their top candidate," They proceeded to string me along for another three months, just for them to tell me that they aren't extending any offers anymore.
The rejection I'm okay with. The thing that just really annoyed me was how LONG it took for them just to say no. Normally when you're interviewing with the candidate, you know immediately whether you want to hire them or not or at the very least within 24 hours of the interview. And even if I did get accepted I think, based off the wishy-washiness and hesitation from leadership, it really leaves a sour taste when you're trying to create a first impression with the company.