I was 5th row second seat to the end of the aisle at house left. Seats were superb. Only missed Phoebe against the closed door during "I've Decided to Marry You" and part of the scene with Sibella and Monty that leads into the number. Granted, these were the $69 rush seats. Still, it was $69 well spent.
Well when I saw it March 29th pre-Tony madness, I got $35 rush tickets left orchestra, with aisle seats in row S (last row), and had no issues with viewing.
So after all your perfectly lovely recomendations...they put me in the front row, on the side aisle, and I could not see a damn thing. I considered doing standing room for the second half but decided against it, mostly out of spite. I wouldn't recommend rush for a heavily sold show unless there were no other options.
I rushed Gentleman's Guide twice in mid Dec with my wife before the holiday rush. Both times for Wed matinee and were super easy. Both times we piggy backed 1st and 2nd rows orchestra. Both times got rush less than an hour before curtain, might be different this month with them closing, but doesn't hurt to try :)