Shamisen is a traditional Japanese three-stringed musical instrument like a guitar. この表現は自然ですか？

Shamisen is a traditional Japanese three-stringed musical instrument, similar to a guitar.

If you say "three-stringed like a guitar," it seems you are saying that it is like a guitar because it has three strings (although a guitar has six strings, so it doesn't make sense).

But if you use a comma, and say that it is similar, then you avoid the confusion about why it is similar.