After having owned a pair for a little over a year, I'm no longer comfortable being on the range with unfamiliar people unless I am wearing electronic muffs. It's just so much safer to be able to hear what is going on around you. They're wonderful for competition or classes because you won't miss any instructions you needed to hear.
That Said (TM), not all electronic muffs are equal.
The ones I've got are Radians ProAmps. They are affordable and that's the nicest thing I can say about them.
They're slim, which is good for long guns, but they are physically uncomfortable. There isn't quite enough room for my ears inside them, and there's no real padding between my ears and the very very hard and uncomfortable electronics. To be fair, the uncomfortableness is probably more noticeable to me because I often wear them for 6 hours or more in a day. But they are uncomfortable from the moment I put 'em on.
They aren't very sturdy -- the plastic hinge on one side has broken & been repaired, and the plastic covering for the head strap is peeling off. Again, to be fair: I've used them very heavily, tossed 'em into my bag with the rest of my gear, and haven't babied 'em, so maybe that's my fault.
Sound quality is pretty good. The volume is separately adjustable for each ear, a very nice feature. Unlike some other electronics I've used, these are pretty good at giving you an idea which direction the sound is coming from.
They use AAA batteries, three per side, but the batteries do last a fairly long time before they start to go south. You can't change the batteries without a screwdriver. What a stupid, annoying, obnoxious "feature" that is!
Most damning thing about them, and the reason I'm looking for another brand, is that they simply don't exclude the noise like they're supposed to. I have no idea what they're rated to, but it is physically painful to stand next to someone shooting a .40 or .45 in the dark house. That's just not acceptable.
So even though I would definitely recommend electronic muffs in general, I wouldn't really recommend Radians ProAmps. I'm in the market for a better set.
pax