I wrote these in a private email to someone a year ago when the new icons were being introduced. Some of them got fixed since. Most did not.
Mostly in the order of decreasing severity:
* The new icons look very distinct from the old icons (just look at undo/redo or next/previous, and compare to the new arrows and carets). Annoying how no one thought to redraw basic things like these or a help icon in line with the new design.
* The cross-out lines are in different directions in different icons
* 'betaLaunch' being English-specific (and just plain stupid, seriously; we don't need visual puns in icons, they're supposed to be intuitive)
* 'stop' icon having inverted color scheme
* 'templateAdd' icon resembling nothing at all
* 'userInactive' icon looking stoned
* 'articleCheck' RTL having a flipped tick, unlike the 'check' icon