Besting the bonds of glue!
We have two MacBook Pros both with failed or failing batteries. The estimate for professional repair was 3 times the cost of iFixit's kit, including the additional tool kit with the heating pad.
The plan was to replace the battery in the MacBook Pro (13-inch, Early 2011) first to build my confidence. The replacement took approximately 7 - 10 minutes depending on whether I include looking for escaped screws. Now on to repair the newer MacBook Pro (Retina, 13-inch, Early 2015) with the assistance of iFixit's repair guide for this model and the tool kits. I elected to use the heat method in order to remove the battery. The process was aided greatly by iFixit's instructions, all that was needed was someone to encourage more patience for the heat pad to do its job. Once the necessary time and heat was allowed to do the softening the removal was completed without event. Placing the new battery was accomplished by reversing iFixit's instructions exactly. The step-by-step guide made the repair a successful endeavor. I bookmarked your site for I am sure these devices are going to become more complicated to repair as we move into the future.
The additional tool kit with the enclosed parts tray was indispensable for containment of all the small parts. I found the heat method to work well without fumes. The glue not raised with the battery was easily removed just gently pulling on a loose end. The iFixit kit and instructions were not only indispensable in helping to complete the task physically, but they also provided the support that built the self-confidence necessary to complete the battery replacements. This was especially true in the replacement of the glued-down battery. Note the time differences in replacing the glued-down battery as opposed to the battery replacement in the older computer that utilized screws. I appreciate this iFixit experience because it points to the need for designers of equipment to design with owner-driven repairability in mind. After all, that is part of ownership!