Well, not quite "normal." ACE Day is really the park's "Dry Run Day" in which people are allowed in and the park tries to simulate an actual operating day so they can find and work out any kinks. Last year it was discovered that Outer Limit's trains were configured wrong, causing a problem for larger-sized riders.
Last year it was about 30 degrees that day and most attractions were closed for weather, so I can't comment on that. PKI did an awesome job for ACErs though, as we got awesome hard-hat tours of the Son of Beast construction site, an optional backstage tour, and a cool catered dinner inside the Festaus.
PKI's service for ACE never ceases to amaze me. You've got the free preview day, half-off any regular day admission ticket, walk-backs for the first ride of the day on SoB or Beast, (new this season) a free SoB poster with every visit, and plenty of other goodies as witnessed by many at the off-season events. Jeff Seibert and his team do an amazing job down there!