The New York Islanders drank champagne from the Stanley Cup here Sunday night and discovered they still savor the taste of success. Their immediate problem is the fact that everyone expects them to win and if they don't make it four in a row next year, they are likely to be severely criticized, says goalie Bill Smith.

"Look at Edmonton," said Smith, first goalie to win 15 games in one playoff year. "Everybody had them paired with us and now people are crucifying them. If we had lost to Pittsburgh or the Rangers, they would be crucifying us."

The Islanders survived their five-game first-round series with Pittsburgh, but it was a near thing, as they trailed by two goals with six minutes left in the climactic game and pulled it out in overtime. They enjoyed a little luck, but they also coped with unbelievable pressure.

"It's really tough when everybody expects you to win," said Coach Al Arbour. "A lot of character really showed up there. There was a lot of pressure and the players handled it and channeled it in the right direction. We had to play tough and play smart--initiate, not retaliate. Winning is fun. We've got that saying on the board in our dressing room."

"We have a lot of fun in our dressing room and I think it comes from winning," said Bryan Trottier, who set a playoff record with 23 assists. "We have a system. Al's system, and we just go out and execute. All we have to do is concentrate. I don't think we're going to abandon our system until someone comes along with a better one."

Since Vancouver was able to score only one goal in the two games here, as it was swept in four straight, it would appear that the opposition has not yet found a better system.

Vancouver's Roger Neilson, considered one of the more cerebral of NHL coaches, could find no antidote to the Islanders' potent power play and relentless forechecking. Neilson pointed out best the woes that confront the Islanders' foes.

"Trottier is the best player in the game today, (Mike) Bossy is the best scorer in the game today, (Denis) Potvin in the playoffs is the best defenseman in the game today and Al Arbour is the best coach," Neilson said. "The supporting cast is all workers. They're by far the most powerful team in hockey. They are strong in all positions, they can play a checking game and a tough game. They have the best power play in the game. And they have good young players coming up."

The Islanders' Indianapolis farm club won the Central Hockey League championship, with goalie Kelly Hrudey and defenseman Mike Hordy selected to the first all-star team. The Toledo farm captured the International Hockey League title.

The Islanders, who commenced play as an expansion club in 1972 and wound up 12-60-6, have become a dynasty largely because of General Manager Bill Torrey's astute drafting.

Potvin's contract is up and signing him could be a problem, depending on the outcome of negotiations with the Players Association over free-agent compensation. New York can win without Potvin, but he is a key figure, particularly on the power play, which wiped out the penalty-prone Canucks with eight goals in 20 chances.

The Pittsburgh near-miss probably took care of future complacency. Injuries are something else and the Islanders have been blessed with a relatively small amount. Still, it must be remembered that Potvin and Trottier played hurt in the 1981 playoffs and Bossy, despite scoring 17 goals and being named playoff MVP this time, was restricted by a bruised knee.

Smith thinks the Islanders' success was born in disaster, when they lost a quarterfinal series to intimidating Toronto in 1978.

"We had a couple of accidents, against Toronto in '78 and the Rangers in '79," Smith said. "We had our hard times. We weren't willing to get hurt to win. Toronto ran us and everything else. The turning point was the Boston series in '80. They tried it, but we decided it couldn't happen a third year. We were willing to get hurt to win. We still are."