El 15-inch MacBook Pro with Retina Display was not highly rated by iFixit in terms of facilities when making repairs is concerned. Its thinning and reduction in thickness led Apple to take unpopular measures among users such as extreme integration of components or batteries whose replacement is really difficult.
The 13-inch model presented on October 23 has already passed through the iFixit laboratories and follows exactly the same steps as its older brother. With a score of two out of 10 (a ten means that it is very easy to repair), this laptop still has batteries stuck to the case, pentalobe screws to make it difficult to access inside, RAM memory soldered to the motherboard and a screen that is impossible to disassemble.
Although a Mac is a computer that does not have to give any kind of problem over the years, its few expansion options (especially at the level of RAM), may force certain customers to choose other alternatives to avoid headaches before any problem.
More information - Forget about upgrading your MacBook Pro with Retina Display
Source - iClarified