I would have to disagree. In my experience, it's the opposite. About 5% is poorly built. My advice, don't buy the cheap stuff. Ikea has a lot of it on display, but it doesn't make a large proportion of the assortment.
I furnished a whole apartment from IKEA and 7 years on and 3rd renter (yes, I rent it) and it's still fine. The Kitchen, the closets, the chairs. Honestly, just because you have to put it together it gets a bad rep. I used to collect money to get IKEA stuff. When I finally got it, putting it together was something my wife and I REALLY looked forward to. It was like playing Legos all over again. And my wife likes it! It's genius. They're the Apple of furniture. Complain all you want about your pet insignificant peeve about it, but it sells like hotcakes and the customers absolutely love it.