John Myers and his sister Betty Politz won't soon forget opening day at parx (no capital letters) casino, the $250 million adult playpen that opened yesterday on the grounds of Philadelphia Park Casino Racetrack in Bensalem.

Before the nation's newest gaming hall was six hours old, Newtown resident Myers and Politz, who lives in Warminster, had won matching $1,000 prizes on their respective "Golden Chariot" five-cent slot machines. But their haul (even figuring in a subsequent $150 hit by Politz), was nothing compared to the jackpot the casino's operator, Greenwood Gaming & Entertainment Inc., no doubt hit on the property's opening day.

According to parx spokesperson Carrie Nork Minnelli, some 200 eager gamblers had lined up in the frigid air before the 6 a.m. opening. By the end of the day, she estimated, 15,000-20,000 people were expected to have visited the 260,000-square-foot gaming parlor that boasts more than 3,300 slot machines and electronic versions of table games like blackjack and roulette.

Before noon, parx's 120,000-square-foot casino floor looked like that of an Atlantic City gaming hall on a summertime Saturday night. The majority of the slot machines appeared to be occupied (although there was no visible action in the high-limit area). And all but a few of the 30 video-poker machines embedded in jax, a mid-floor sports lounge, were in use.

By and large, first-day customers praised the new facility whose modern, elegant design and decor raises the Pennsylvania casino gaming bar. Cathy Richey of Princeton, N.J., was particularly impressed.

"When you walk in and see the lights in the ceiling, it's very pretty," said Richey as she grabbed a sandwich in Foodie's, the complex's food court. "It's open, it's airy, it's just great."

Sharing those sentiments was Richey's friend and casino companion, Lois Vendetti of West Windsor, N.J. "I love it," she enthused. "I think it is fantastic."

Even if he hadn't hit his 1G payoff, Myers still would have come away with a favorable impression. "I've been to all the casinos in Pennsylvania, this is the nicest one," he said.

Of course, no opinion is ever unanimous. There were a few complaints heard yesterday. For instance, Janice Preston of Willow Grove griped about some technical glitches she encountered.

"Lots of machines aren't working," she said as she motioned toward a bank of five slot machines, two of which displayed "Out of Order" messages. She added that she thought parx could have done a better job of delineating the locations of the nonsmoking areas, but added, "the design is really nice."

Preston's best friend of 50 years, Linda Harmon of North Philadelphia, was more generous in her appraisal. "I like it much better than the other one," she said of the temporary facility in the racetrack building that housed the slot machines for the past three years.

"I'll come back."