I give it a big "it depends"
If you are pressed for time, or someone in your group is afraid of heights, or you want to spend a decent amount of time exploring the displays on the 1st and 2nd floor, then I would say don't go to the top.
If you have plenty of time, you want to be able to say "I went to the top" and no one is claustrophobic (elevators), afraid of heights, or has a problem waiting in long lines, then go for it.
If you want to go to the top - go early in the day. There are lines for tickets, but there's also a line for the second elevator that goes to the top.
Honestly, I don't think it's worth the extra time/money. You can see further, but you're so far up it's harder to tell what you are looking at. The lines can be quite long, the deck quite crowded. But you do get to say that you went to the top of the Eiffel Tower. If you do go, you can always use the bathrooms up there as another "I did it" experience.