I work there, in LA. I started there out of college and was never an intern.
Busy season has not been bad, at least for me. No 18 hour days, work in the early hours of the morning, or anything like that. Not sure if you're coming in audit or tax, but the audit dept in LA targets 55 billable hour weeks during busy season, and there is actually a lot of work done from the office. Expectations are reasonable for new staff.
Offices from the old Reznick side will be more affordable housing/commercial real estate focused, while old JH Cohn offices will be more diversified, but the firm is trying to grow more diverse practices in the old Reznick offices. LA is unique because it was the first integrated Reznick Group-JH Cohn office (the JH Cohn half itself the remnant of an old LA firm). As a result of the merger, LA has a great diversity of industry practice: affordable housing, commercial real estate, hospitality, retail, manufacturing, tech, and NFPs, among others.
The firm has a good reputation with public company audits, but it doesn't audit many of them (LA is no exception). It's really committed to the middle market.
My guess is that your experience will depend on the office that you've been hired at. A lot of the firm's growth is fairly recent merger/acquisition-related, and offices often will work and feel different as a result.