The Dropbox interview process was pretty okay. It was very long, and they saved the hardest questions for last, when you're already exhausted.

Sometimes, interviewers will be intentionally vague and still won't answer questions. Other times, they want to see what assumptions you make when forced to fill in the missing pieces yourself. Sometimes, they just want to see if you can ask the 'right' questions, which they will then answer. It's definitely a frustrating back and forth to do with every interviewer just to find out what they want.

Lunch was nice at Tuck Shop, and the building is pretty much like every other tech building. They have a lot of perks, but not on the Google/FB level.

They do a tech demo of the things they're working on and then push you to make a team choice at the end of your interview. It's nice that they listen to you about what you want to do rather than assigning you somewhere, but making a choice like that is hard to do on the spot at the end of an exhausting interview. Also, keep in mind that picking a team to join and getting the tech demos are not in any way related to whether or not you get an offer. In hindsight, it seems like a huge waste of mine and their time to do those things before a decision has been made.

Also, if you want feedback, try to get what little you can as you leave. They won't provide any after the fact beyond the typical "blah blah" that they tell everyone ("it was a really, really tough choice for us, blah blah").

Of the individual interviews I did, three had good, engaging interviewers, and two were pretty poor with lackluster interactions from them. Overall, the interview was average difficulty, with the exception of the concurrency curveball. If you can manage that, then their interview is trivial with good interviewers.

I definitely recommend studying up on concurrency for the interview, in the language of your choice. If you can build a basic image link downloader or web crawler with multithreading, then you should be fine on that one part.

The interviewer will be of no help, so you must memorize every API call and piece of syntactic sugar surrounding concurrency.

If you aren't familiar enough with the syntax, then you won't be able to demonstrate that you understand the most basic concurrency concepts properly. It is not a discussion question; it is very much a whiteboard, multiple threads in 30 minutes question.