This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
Our II+ ran flawlessly for nearly six years before requiring a new power supply and keyboard IC replacement. A veteran of countless experimental mods, it continues to perform well. Our IIgs, on the other hand, is presently on its third motherboard! (Actually, it may be the fourth; it's hard to be sure. I do recall that one of the replacement boards didn't do anything, except short out the power supply.) The main problem is an apparently endless supply of sub-spec proprietary IC's (e.g. video and ADB controllers). So, why three (3) motherboards!? Well, Apple does not allow its local sales/service reps to replace soldered-on IC's. Should your ADB controller bomb (or, more likely, you finally discover that it has been sporadically malfunctioning all along), "repair" consists of swapping out the motherboard. If your warranty has expired, the cost is $270 plus your old board! As to old complaints-- a II series marketing strategy designed to create a toy image, high prices, slowness in releasing documentation, Mac exploitation of II events, etc., etc.-- elaboration is hardly necessary. The record is one of studied insult, rapacious greed, sloppiness, and dismal neglect.