It's a good episode. It's not one of the best, but it is needed. Phoebe contemplates whether she should carry her brother and sister-in-law's baby. Joey, needing job, becomes a tour guide at the museum where Ross works.
It is a filler episode, a let's get to the action one. This episode introduces us to Phoebe carrying the baby. Without it we would jump into Phoebe being pregnant and that would be just be weird not knowing why or how she got there.
Ross and Joey's storyline together is good. Joey breaks down the walls at the musuem and he's funny, of course.