Looks like it's 16/day to start with, albeit with some variability in frequency throughout the day. I'd like to note that I think running the first train from MIA at 0650 seems questionable to me.
That said...it'll let me day-trip to visit Mom and Dad (and leave Boca after dinner) or visit them and side-trip to Disney for a day (and leave around the time several parks close in winter). So...not bad.
[BTW...I don't see any expresses timetabled, just some trains skipping Boca.]
Edit: Another curiosity - I'm seeing an 0400 [!] from WPB-MIA on Saturdays but not weekdays. That gives an 0545 departure from MIA to MCO (arriving at 0915, displacing the 0650 departure).