However, there were aspects Saturday's victory at the Liberty Stadium that left him wanting more.
Welsh international half-backs Rhys Webb and Dan Biggar ran the show, scoring 26 of Ospreys' 31 points between them - a Hanno Dirksen try completed the result.
Tommy Bowe and Rob Herring each dotted down for Ulster but the Irish province slipped out of the top four with defeat.
"I am happy with being top of the table at Christmas and reasonably happy with the performance," Tandy said. "For 55 minutes I was extremely pleased with a lot of what we had done.
"After that, I was a little bit disappointed, frustrated and annoyed with some of the penalties we gave away. We let Ulster back into the game.
"We got a bit loose, but I don't want to take away from the first 55 minutes because it was a decent performance.
"We played a lot of good rugby and to get the bonus point as soon as we did and beat a side like Ulster is decent for us.
"But we need to keep our feet on the ground and we have three huge games coming up."
And Tandy was satisfied with British & Irish Lions flanker Dan Lydiate, who came off the replacements' bench to make his Ospreys debut.
He added: "It's great for him to wear the jersey and you can see what it means to everyone.
"It was a nice game for him to come on in. It was not really difficult to leave him out of the starting side and I thought James King was exceptional last weekend.
"We want Dan to settle in and don't want to push him in too early. We are also respectful of the boys we have and what they have done. Dan will have his time in the jersey as will James."
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