The world No13 can be unpredictable on the court - last year in the Nice final he won four consecutive points with drop shots to win a crucial game - and you never know what you are going to get. He can be controversial but most of the time it feels like Ernests is just being earnest.
As an example, how does he handle the mental side of the notoriously tough sport?
"You think I am handling it? I don't think I am handling it ... ", he says with a laugh.
Or witness the following exchange.
Herald: "You've beaten Roger Federer, Novak Djokovic, Andy Murray ... most of the big guns. What will it take to beat them more regularly"?
Gulbis: "Playing better" [grins].
Herald: "And what does playing better mean for you? Where does it come from?" Gulbis: "From practising, from playing better [laughs].
Herald: "Okay ... when you have beaten them ... what has gone so well?"
Gulbis: "Okay, I'll give you an honest answer. It's all about a lot of matches for me. When I beat Federer [in the French Open] I was on a roll of more than 10 matches and I came to Paris and played well. It's the confidence. I don't think you can beat guys like this in the first match or second match of the tournament; it's tough if you haven't been in a good way."
That's Gulbis to a tee. Cheeky and confident, but also insightful and honest. The Latvian burst on to the scene in 2008, when as a teenager he made a run to the last eight of the French Open. He was an exciting talent, with an attacking style and unique personality. The man from Riga could beat just about anyone on any given day but those days didn't come often enough.
But he attracted attention for his inclination to court controversy. He once said that the likes of Federer, Djokovic and Murray were "boring" in interviews, lacking the spice of past rivalries like Jimmy Connors and John McEnroe. Last year at the French Open he said he wouldn't encourage any future daughters into tennis, as it is too tough and women "should focus on family and kids". And in 2009 he spent one night in jail in Sweden, arrested for allegedly soliciting prostitutes after a "misunderstanding".
"When I meet a girl, I don't ask her what her profession is, I don't ask if she's a hairdresser or something else." he said afterwards. "If you go out and meet some girls, and immediately you're put in jail; that's not normal. So I'm upset with the Swedish Government [but] I think every person should go to jail once, as it's interesting." He has always been prodigiously talented. Gulbis was pushing Federer when the Swiss was at his peak, he has 16 wins over top 10 players and is unbeaten in singles finals (6-0) - but there was uncertainty about his desire and work ethic. A cerebral character, he had many other interests and didn't seem to suit the relentless routine of top level tennis. Not any more.
"Now I understand what I really want," says Gulbis. "When you are 14 or 15 or 18 you are still searching for what is your true enjoyment. Now it is pretty clear. I matured a couple of years ago and now I am really started to get into it." Last season was his best yet. The 26-year-old cracked the top 10 for the first time, won two titles and reached the semifinals at Roland Garros, beating Federer and Tomas Berdych on the way.
"My first half of the year was great," says Gulbis. "If I get the consistency right for the whole year then I am top eight for sure." Gulbis has already fitted in a day's sightseeing in Auckland, visiting Great Barrier Island and Waiheke Island. "Last time I was here I lost to [Juan Martin] Del Potro [second round, 2009] ... not a nice memory," he says. "And I didn't go anywhere. Just the site and the hotel. So this [time] is already better." And the best is yet to come.
