Is the "All Asians are smart" stereotype a good stereotype or a bad stereotype?

There are no good stereotypes.

Here is why it's not a good stereotype: a poor performing Asian will then be seen as yet more lazy/less wise than a poor performing non Asian. Not all of those who poor perform are lazy. Sure many of them are to some degree, but some may poor perform out of their control while not knowing that help is available and while not knowing that they can do better with some people giving the explanation that is just right for them. Some are afraid to ask for help because they're afraid that teachers will think they didn't pay attention, aren't trying hard enough, are making a fool out of themselves, or are playing around, which tragically a few teachers actually think that from students who ask for help. When someone is put down in certain way that belittles in a long period of time and the person has tried finding countless different solutions but none worked, they turn to suicide. This can especially be so for some Asians as they fear that they will be seen lazier or dumber than an average person, especially if he/she as an Asian isn't lazy. Stereotypes of all kind must be put to an end.

All though it would be a positive stereotype at first glance, looking into it actually reveals the negatives of it. This stereotype is an expectation, such as the one in the US that Blacks are more likely to be criminals, and when they can't stay above this expectation they can be harshly teased. In Japan they have extreme expectations in school lives that stress them to the point of suicide. So yeah, it's a pretty negative one.

No it isn’t. It puts to much expectations on Asian kids. It’s stressful having that much expectations on you.

This stereotype places higher expectations on Asian Students and they are driven to perform better. it also exposes Asian students to harder topics in school projects, which the teacher might feel more comfortable giving it to them. it is a positive cycle of expectation/motivation/reinforcement

As you say, there's pressure to be smart. Stereotypes have power- people strive to be in that category. I benefited from a different but similar stereotype regarding glasses- while a large part of my academic success is luck, it certainly didn't hurt to have social pressure encouraging me to try harder. If a stereotype helps people to excel, then it's good in my books.