Is it worth buying the textbook for the course and did you use it to further enhance concepts or was it used more for reference during the labs?
Thanks.

I didn't get the textbook, and I did well in the class. One lab required the textbook to look at some figures, but someone else in the lab will surely have the textbook, and probably your TA as well.

I found the textbook incredibly helpful, especially if you miss a concept in lecture or are confused about a topic. It's 3.5 years later and that text is still relevant for me; it is more of a book that you can consider an investment than "just assigned readings for a course". I imagine the labs have changed since I took the course so I can't quite comment on those but the text in itself is solid and worth the money.