The one keyboard shortcut that I use all the time, W4 to remove doubles, is now W5. W4 collapses verts, and is also useful, but shouldn't new features/functions be added to the end of the pupmemu? Does anyone agree with me on this?

yup, people complained about similar problems in the delete menu of 2.27
(and shift+o becoming toggle subsurf, when it was toggle proportional vertex falloff type)