Just some precision because this is really good work.
For the past 3 years at least, the existing Decompiler used in Pharo has not been able to decompile correctly all the methods of the Pharo image. We proved it by recompiling all the methods using their decompiled sources: this operation was crashing the image as some methods were installed but not correct.
With Kevin's Decompiler, the image can now be recompiled from decompiled sources, still works fine and all the relevant tests can be run successfully. Hence all the Pharo methods covered by tests or used by normal development process are proven to be correctly decompiled.
Therefore, his Decompiler has proven to be better the the existing one.
I also believe that his Decompiler is overall simpler to understand, but software simplicity and readability is always very subjective and arguable so I let you guys have your own opinion on that matter.