Things couldn't be better. Is that good or bad?

I bumped into one of my students I used to teach on the street the other day. He asked how I was and I said that it couldn't be better. He looked confused and wasn't sure if things were good or bad.

If xxxx couldn't be better it means that things are going very well. So well in fact that it can't get any better. Let's look at some sample situations.
Waiter: How was the lobster ravioli?
customer: It couldn't be better. The lobster was scrumptious!

A: How was the Caribbean cruise you took last month?
B: It couldn't be better. My cabin was gorgeous and the seeing the sunset every evening from the deck is unforgettable.

Of course sometimes things don't meet our expectations or we weren't completely satisfied or happy with the results. In that case, things could've been better.
A: How was your stay at the Ritz?
B: The service was very good but the room could've been better. I had a mediocre view from the room and the pillows were too hard.

A: How was the (Los Angeles) Lakers game?
B: They won the game but they could've played better. They had a big lead but then they started playing poorly on offense.

Tell us about a very satisfying experience you had. Or tell us about a time when things could've been better.