I have one and only one reason for hating IKEA, before IKEA furniture was delivered fully built, then IKEA disrupted the market by having people build their own stuff, which, among other things, allowed them to be significantly cheaper. Now, at least were I live you can't have furniture delivered pre-built (unless you buy antiques) but you can hire a handyman to come build it for more than the price difference was between unbuilt and built before IKEA came to dominate.
Aside from that I understand text better than I understand graphics so I am always at a disadvantage dealing with IKEA build instructions, having to go through the drawings 4-5 times trying to identify where two pieces look almost exactly the same but have a significant little difference that must be paid attention to - something they could easily do with a single sentence on the relevant pages describing the differences.
Actually then I guess I have two reasons I hate IKEA.