This is one of the more popular episodes of "Futurama" but time travelling story-lines either work well or they don't work at all. "The Why of Fry" is a fun episode but is hardly as perfect as everyone makes out. There are some decent gags, but not nearly enough, and the plot is interesting until the time travelling stuff at the end, which makes absolutely no sense whatsoever when I think about it.
Overall, I preferred "Futurama" back when it was starting out and was more about the jokes in idividual episodes than the amazing science fictiony serial it's wanting to be here. But it still has its moments this.