I think that, technically, I'm not supposed to review Shakespeare in the Park's star-studded Twelfth Night because the previews just started. But...I did see it fresh out of rehearsal on Wednesday night and greatly enjoyed it—as did Trapezia and many other attendees who laughed heartily at the play's many comic episodes—so I encourage you to go scurry over and see this production, which officially opens June 25 and runs until July 12.
As good as the production already is, I think there's room for improvement. These are preview performances, after all! Anyway, it's reasonable to expect the proceedings to improve as the actors develop their characterizations and delivery. But that's no reason to hold off until the ticket situation becomes unbearably competitive. See it now, get it over with, and then, if you're really into it, you can always try to see it again later.
If you can't get in the daily ticket line by, say, 10:30 am (what turned out to be the cut-off time on Wednesday), you can still get in the virtual line (which worked for me!) or even drop by in the late afternoon or evening and see if you can get a stand-by ticket. (Just remember: the stand-by line is "one ticket per person, with absolutely no cutting or place-keeping. It looked pretty encouraging around 6 pm on Wednesday night, but the situation will probably become more difficult moving into the summer.)
On a pseudo-scholarly note (possible spoilers follow), I've done some research that helped me appreciate how Shakespeare's wordplay extended to the use of anagrams in naming some of the work's characters. There's also a play on words that anticipated the Britney Spears ditty "If You Seek Amy" by centuries. On top of that, there's a famously puzzling riddle involving the letters M. O. A. I. I've whipped up my own "solution" to the riddle, but you'll have to check the comments for that potential spoiler.