I've switched for years between using these and Ernie Ball's Heavy Bottom Slinky Top, which are the same gauge. I've found that the D'addario strings snap less easily, particularly the high strings, and seem to be more resilient to energetic playing. I don't play very fast metal or lead lines often, so they don't come under a lot of stress, but I've found that they seem to hold tune a bit better than the Ernie Ball strings on the same guitar in the same room. They seem to settle in to their tuning from being strung up quite quickly, and their 'slickness' stays for a fairly long time, although they do get buildup and rust at roughly the same rate as other standard string brands (without moving up to coated strings). I have found a few times that the tie at the ball end of the string can come undone and break at that end with very heavy playing, particularly on my jaguar and jazzmaster where they may come into slight contact with the tremolo plate screws by vibration, but it has not happened that often and so I have persevered with them for now.
These strings stay quite bright sounding even when they are getting old and need replacing, but can sound a bit harsh to begin with, which I don't find with Ernie Ball strings. Overall though, I find the D'addario present better value.