Estimated at 53 Million "First Class" isn't going to beat the "X-Men" opening weekend of 54 Million +. If you adjust "X-Men" for inflation it beats "First Class" by a wider margin. Not to mention "First Class" opened in 3600 + theaters and "X-Men" opened in 3025 theaters.
The hold for "X-Men" is in it's 2nd weekend was 56.92 %, pretty standard for a major tentpole. Not bad, not great. Then it held impressive after that. 45.97%, 46.67%, 38.83%, and 38.30%. It will be interesting to see if "First Class" holds well with the only major competition being "Super 8" next weekend, which is a wild card. After that it will have to fend off "Green Lantern" & "Mr. Poppers Penguins".
Not a bad opening for the flick, below studio estimates, but not necessarily bad. Sequel talk is premature at this point, but by all accounts the movie is damn solid. I haven't seen it yet, but can't wait to see it. Isn't that all that matters, "First Class" being an entertaining movie filled with your favorite characters and doing said characters justice on screen?