Took USMLE Step 2 (a 9-hour exam) here on a Friday and it was FINE, like TOTALLY OKAY. I was super stressed by all the negative reviews about the neighboring kids' music school, especially because I need pindrop silence when testing. I was even considering driving all the way to Tucson to avoid this dilemma.
Turns out this testing center was awesome - my regular foam earplugs (Flents brand) + Prometric earmuffs on top (provided by testing center) were more than enough and I didn't hear any sound at all except my own heartbeat. I experienced zero disturbances at this center. If you're stressed about sound, just practice studying with earplugs at home.
The ladies working at the center were crazy nice and super efficient with getting people in and out during breaks. Yes, during breaks there were little kids sitting in the main area waiting for their piano lessons with light chatter, and yes there is only 1 bathroom - but overall this wasn't a huge issue. The desks in the room are connected but have private dividers with plenty of space so there's privacy. I didn't get distracted at all by sound or ppl moving in and out.
Overall, this testing center was 10/10 and honestly way better than any of the 3 Prometric centers I've been to in CA. You'll probably be okay.