I did a small project so maybe someone that did something larger can weigh in, but I worked with RethinkDB back in the 1.4 era, so a bit has changed, but the biggest difference IMO is that you have to be prepared to fall back to the RQL syntax to do queries more complex than simple get etc. vs. in Mongo everything was in JSON, and when I was using Mogno you couldn't join tables at all, don't know if that's changed and here you can. Otherwise it is pretty similar, since I didn't do any clustering.