I just did my first Hyrox (Men's Open) this past December. Here are my thoughts:
1) Personally, I found the energy at the event to be overwhelmingly positive and invigorating. Other than not knowing your start time until three days before (mildly annoying if you're trying to make travel plans), it was pretty well organized.
2) As others have mentioned, running features predominantly in Hyrox. Having a strong base will help immensely even if you are mediocre at the weights (like me). The pacing guidance you'll commonly hear is to aim for somewhere between HM and marathon pace. This worked for me.
3) Yes, you need to weight train. I didn't necessarily perform many Hyrox specific workouts (i.e. alternating between runs and weights without rest) but I did put hands on most of the equipment and practice most of the movements. Of note, even before I started training for Hyrox, my normal weekly gym routine already incorporated multiple sets of back squats, Bulgarian split squats, overhead press, bench press, pull-ups etc. Exercises like the ones I just mentioned will help build baseline strength while you start practicing the Hyrox stuff. Rawdogging a Hyrox without any weight training is a recipe for rhabdo.
4) Finishing a Hyrox feels great. Actually doing one is hellish. Unlike a 10K or other race, your heart rate is fluctuating wildly as you alternate between stations and runs. Overall, I would say the effort is equivalent to racing a HM.
5) Hyrox has been picking up in popularity. Hopefully, this translates into more events in the US.