I like them. They make the slide a little grippeir, but they're not so big that they get in the way. I've not yet attempted to CC this one because I'm lacking a proper holster, but I do not see that they'll cause any problem.
They do have an unusual appearance...probably because I'm not accustomed to seeing them on pistols. The look is growing on me though.
So essentially...
Does one need them? - No
Might they provides some benefit? - Yes
Do they cause any problems? - No, not that I've been able to ascertain.