It greatly depends on your professor that you work with.
My experience is that you can always decline it if you see that there is no fit or if the time commitment is too high.
Usually these assume a certain number of hours (such as 10 or 20 hours per week). Sometimes it ends up being just an hour a week or lasts only half the time since professors don't need help the entire term. In other cases, it may be something that you spend quite a bit of time on.
In 90% of the time it is very much worth it:
- Easy money
- Usually interesting assignments
- You get to know the professor (which depends on the prof - may be an opportunity of a life time esp. for some stellar guys)
- You can decline/quit though it will be a sour point in the relationship with the professor
Generally this is very positive and students compete for it.
Founder of GMAT Club
Just starting out with GMAT? Start here... | Want to know your GMAT Score? Try GMAT Score Estimator
Need GMAT Book Recommendations? Best GMAT Books
Co-author of the GMAT Club tests
Have a blog? Feature it on GMAT Club!
Get the best GMAT Prep Resources with GMAT Club Premium Membership