When "Late Night with Conan O'Brien" premiered in September 1993, the critical reaction was not exactly enthusiastic.

To be blunt, the show was more or less savaged by most critics (including this one). But O'Brien isn't holding a grudge."The press was, I think, justifiably skeptical," O'Brien said ecently. "People ask me, `Are you bitter about that?' And I think, `No, I'm highly paid. I asked for it.'

"And to tell you the truth, I would have been very skeptical of the person replacing David Letterman and probably would not have liked him for three or four months. And here's where it gets weird - even if it had been me."

Of course, it was a lot longer than three or four months before viewers started to come around as far as O'Brien was concerned. Even his own network, NBC, was hardly supportive - he worked under a series of contracts as short as 13 weeks and had the ax hanging over his head throughout his first couple of years.

And he admits that his show went through some major dif-ficulties.

"Not just with the press but with our own network, with the ratings, with the guests, with just figuring it out," O'Brien said.

Still, he insists he didn't resent the harsh criticism of both himself and of his show.

"I would have said, `What's wrong with his hair? And why is he laughing like a hyena? And he's too fidgety. And why are they using puppets so much?' " O'Brien said. "It was a really difficult assignment, and there was part of me that felt, `Well, this is what I should get from the press and I don't blame them.' "

These days, of course, O'Brien's position is much more secure. His "Late Night" ratings have increased dramatically, and his contract will carry him into the year 2003. Gone are the days when the show could only dream of A-list guests and usually had to settle for, not B-list, but C- and D-list.

"Let's face it. My show couldn't get great guests," O'Brien said. "I think we all remember those days when Dr. Ruth Westheimer was on four nights in a row - and we weren't discussing sex. But things have changed and now we have big stars on our show."

It's not the big movie stars or the beautiful supermodels that he gets excited about, however.

"For me, it's been meeting people like Andy Griffith," O'Brien said. "I remember as a child watching Andy Griffith and so when I met him, it's this almost out-of-body experience. He's an icon to me. He's Lincoln on the penny. He's this figure that was otherworldly to me. And now he's sitting next to me and he's addressing me by my first name!"

It was another guest that O'Brien said helped turn his failing version of "Late Night" around - the show's previous host, David Letterman.

"David Letterman came on our show when we were just about 6 months old and we were getting the crap kicked out of us by just about everybody," O'Brien said. "He came on as a guest and that was a ratings bump for us. . . . And it was also, I think, a bit of a statement for Letterman to do that. He came on and praised the show and said nice things about it and, at the time, that was a big deal for us.

"Do I think that changed everything overnight? No, but I think if you had to find one big turning point the first year, that might be it. . . . It was a nice bump at a rocky time." Actually, as rough as the first year or two of "Late Night" was, O'Brien said that wasn't the worst time of his career.

"The most difficult time for me, believe it or not, was the time before we went on the air," he said. "I've heard many descriptions of hell. To me, the greatest hell is being famous for no reason."

Back in April 1993, when NBC announced that O'Brien would succeed Letterman (who was defecting to CBS), the only Conan most people had ever heard of was the one played by Arnold Schwar-ze-neg-ger in the movies. And it would be almost five months before anyone got to see O'Brien function in his new role.

"I was a famous person," he said. "I was being interviewed, I was having my picture taken, but I hadn't done anything yet. And people were saying - fairly - `Who the (heck) are you? And what the (heck) are you going to do? And why are you funny?' And those are impossible questions to answer." He recalled passing by a newstand - the same newstand he'd passed by every day for years - and suddenly seeing his face on the front of the papers.

"People dream about that kind of thing and think it's great. It's not great," O'Brien said. "It's a very strange experience.

"You can't help but feel a little stupid. And I think a lot of people were looking at me as an accident waiting to happen. . . . A lot of people were looking at me and saying, `Cool, he's going to be killed! What's that going to look like?' "

Which was even worse than the critical slings and arrows and bad ratings. "Even though when we went on the air, people were critical and obviously I had a lot to learn, at least we were all on the same page," O'Brien said. "I could agree or disagree (with the criticism). And it was all in context." And he rejects the notion that "Late Night with Conan O'Brien" has undergone any big changes on the road to success.

"I don't think we changed the comedy direction of the show that much," O'Brien said. "I don't think we made many overall alterations to what we set out to do in the show. I just figured out how to do it every night.

"Like anybody who's started a new job, it takes a while to figure out exactly how to do it, where the bathroom is, how to act and how to do it fluidly. And I think it took me about a year on the air, at least, to really figure out how to be a fairly decent talk-show host."

He did, however, take the advice of someone who knows something about the job - Johnny Carson.

"About a week after getting this job I met Johnny Carson. And all he said to me was, `Just be yourself. That's the only way it could work,' " O'Brien said. "And that's what you do.

"I didn't learn to be some slick character. I just learned how to be Conan O'Brien in a very unusual setting."