Has anyone used one of these? Is it worth getting one? 

Worth every penny. Make sure to get the tray too, it's awesome. 

How long do they stay in them? My son is 5 months. He is starting to sit up without support for like five minutes. He gets mad if he is not sitting up. will it tip over if the baby moves forward? 

It never has when my son sat in it. He's 10 1/2 months and he just stopped using it, but I'm sure he'll still fit in it if I got him to sit still long enough to try. 

This is something I'll probably buy used. I'm so out of the baby loop. I was looking at "must haves" last night. I'm so overwhelmed! Don't know how my others survived without half the stuff LOL 

They always have them on the YS site, so buying used is not a bad idea. They're kind of expensive brand new. 

They are so awesome!! Both of my kids loved them! It was the only way i couls get anything done wity my oldest. 

I never used one...and I don't think I would buy one if I have another.. 

bumbo was WORTH IT! My 10 month just stopped using his only because he knows how to get out of it! I started using it when he was almost 5 months and he quickly started sitting up by himself right after! It is the greatest to get things done as well. I put him in it while I cook, to watch his tv shows, and to shower! Its the greatest and I highly recommend it! 

Bumbo is fantastic! I got mine on sale at Target for $3.50! ;) I think they messed up that one, haha! OH WELL!