I've owned plenty of Ikea in my life and it kinda just depends. Most of it's well-designed but poorly machined so the more complex it is, the more likely you are to get two dowel holes that only barely line up or a screw hole that wasn't drilled. Most times, you'll encounter no issues at all. And other times, you'll be like me and have to deal with the Norberg, a bastard of a shelf that took me, an experienced woodworker with an entire shop of tools at my disposal, two days and three different screw types to hang on the wall.