2 and a half year ikea employee veteran checking in.
nay.
i worked in returns so i feel confident in the ability to say this.
they are returned on an extremely high basis due to people not liking them. a lot of people also would complain that after a year the padding kinda gives in.
edit:
also for the record, if you do not keep a copy of your receipt they will not cover your mattress for warranty. the company doesn't file away transaction history for more than a year, it 100% falls on you. i've had times where my old managers would refuse a mattress for warranty because it was too dirty or gross so it was there fault. in the event you don't have a receipt they can look it up within approx a year if you give them the date of purchase, the total amount of purchase and the last 4 numbers of your card (they will try to avoid you if you paid with cash) however due to the shitty point of sales system ikea uses, some managers will deny this ability. when they look at transaction history it is sorted using item numbers so its hard for the employees to find what you bought... and only a manager can do this.
AND ALSO, if you do get one. keep in mind the return policy on mattresses is "love it or exchange it" that means you can only exchange it. when they do the exchange you get a store gift card which they claim can only be used on mattresses, this is false. you can use it on anything in the store. some stores put stickers on the gift card so that an employee can't use it on anything except a mattress (but at the store i worked at no employees enforced that). if this is the case and you get a sticker on your card, just use it at self checkout and you should be golden.
last of all. for any purchase at ikea get a receipt. half the shit falls apart in a year. the more paperwork you have to prove your purchase was within a year/reasonable amount of time.. the higher chances you have of getting an exchange or a refund. i would make copies of your receipt and tape them under/behind the product. just make sure you have something to fall back on (this advise falls under more than just ikea i'm sure). if you bring back something broken, chances are they will not try anything to find your receipt in their system.
godspeed.