Hello! I also work at UCI and know a bunch of people in the INP program! In general, students are really happy and people in each cohort are pretty close with each other!
As @BrainsAreJustMeatMachines mentioned, Irvine is a pretty uneventful city but you have a ton of other places within driving distance where you can find stuff to do!
As for chances of being accepted after an interview, I'm not sure if things have changed because of COVID, but grad students have told me that for the most part, as long as you seem like you're a passionate and decent person during your interviews and you don't set off any red flags to the students or PIs, then you have a good shot at getting in!
Best of luck with the interview process and feel free to DM me too if you have any questions about PIs or Irvine in general! I'll try to help to the best of my ability!