Pai is a small tourist town about 3h north-east of Chiang Mai.
There are many minibuses driving there every day, you can just book them basically in every hotel or tourist information center.
I myself drove the way by scooter which was a really nice drive, there are many restaurants and temples along the way.
Some of the Highlights of Pai are:
Pai is well-known spot amongst tourists visiting the north of Thailand. Chiang Mai is a quite big city, and it's pretty busy, so a lot of people want to enjoy the nature and especially the incredible mountains, north Thailand is known for.
So if you like mountains and a nice nature landscape, you definitely should check out Pai.
Yes, it's definitely worth a visit, it's a good place to stay a couple of nights.