还不错。

You can use it as a standalone answer or at the end of a sentence. If someone asks how your day was, just say 还不错. If you are eating a bowl of noodles, you can say 味道还不错 (the taste is pretty good). It is incredibly flexible. You don't need complex grammar to make this work. Just drop it whenever you want to give a 'thumbs up' without being too loud about it.

Use it when you are genuinely pleased but want to keep your cool. It works perfectly at a restaurant when the waiter asks about the food. It is great for texting friends about a movie you just saw. In the office, use it to describe a project's progress to your boss. It shows you are confident and things are under control. It is the 'white t-shirt' of Chinese phrases—it goes with everything.

Don't use it for life-changing, amazing news. If your friend just got married or won the lottery, saying 还不错 will make you sound like a robot. It is too casual for a deep apology or a very somber occasion. Avoid it if you are actually unhappy. If the soup is cold and salty, don't say 还不错 just to be polite; it will confuse people. Also, don't use it to describe people's character in a formal setting.

Chinese culture values the 'Middle Way' or moderation. Being too boastful is often looked down upon. By saying 'not wrong' instead of 'amazing,' you show humility. This stems from a long history of avoiding 'extreme' emotions in public. Even if a student gets an A+, a parent might just say 还不错. It is a way of keeping feet on the ground while acknowledging success.

You can add 挺 (tǐng) to make it 挺不错的, which means 'quite good.' If you want to emphasize it, add 还真不错 (hái zhēn bùcuò) for 'really not bad.' For a very casual vibe with friends, you can just say 不错哦. If you want to be even more modest about your own skills, you might use 还可以 (hái kěyǐ), which is a step below 还不错 on the excitement scale.