PLEASE NOTE: I endorse Elixir strings. They didn't come to me though, I went to them because I really like their product.
There is, or at least was, a bit of a debate about coated strings. Which I completely understand on two levels, first, coated strings, especially early on were not as bright as non-coated strings. And second, one method of advertising is to disparage your competition. That quieted down significantly when many other manufacturers offered up their own versions of a coated, long lasting string.
So why do I use them?
1. I have acidic hand sweat. You should see up close some of the hardware on my guitars. Particularly the gold ones. Not pretty. You know the alien blood from the movie Alien? Now you know what I'm taking about. Prior to Elixirs I used Ernie Ball strings on electric, and within and hour of playing time they became tetanus wires. I was always changing strings. At a few bucks a set it wasn't that big of a deal, just the time it took to change them, but time is money and once I switched to Elixirs I found that I could keep strings on my main electrics for weeks instead of days.
2. They don't corrode in storage. I have a lot of guitars. Many are rarely played. But the last thing I want to do is restring my Rickenbacker 12-string the night before a session. Especially if, despite being told to bring it, I never actually use it. But with it strung up with Elixirs I know I can confidently grab it on my way out the door and if needed it will be ready to track. I always keep extra sets in every case just in case. Pun not intended.
3. The immediate vintage tone. Truth be told, as nice as brand new strings feel, they can sound a little brittle or bright. Normal strings sound better once worked in. For me that may only take an hour, for others a week. Even still I change strings on my acoustic(s) the night before a session so they have time to settle in. With Elixirs they immediately have that worn in sound and I like that. Many players don't and that's why they came out with the nano-web versions to provide that closer to non-coated experience. To me both the electrics and acoustic sets are ready for the red light (to record) as soon as they are on the guitar.
4. They tune up fast. You know how when you string up a guitar you have to tug the strings and tune them a bunch of times until they settle? Maybe between every song for a set? Not with Elixirs. Tune, tug, tune, play, tune... and that's pretty much it from my experience. This is important when you have several guitars out for a session and you are going from one to the other twenty times in an hour.
5. They are quieter. When I'm in the studio recording acoustic instruments, ie. acoustic 6 or 12 string, nylon/classical guitar, mandolin, etc., I am often playing before a very sensitive condenser mic or maybe two. They pick up everything: heavy breathing, toe tapping, chair squeaking, humming, counting aloud, a hole in your septum (that's another story for later) or SQUEAKING STRINGS. Well Elixirs can't help with any of those except those pesky squeaks one creates when one slides fingers up and down the fretboard. There are ways to reduce that noise; mic placement, lightness of touch, swiftness of hand movement. But another tools to reduce this unwanted noise is to string up your instrument with coated strings. I prefer the polyweb (classic) over the nanoweb for this reason.
6. They are easier on the finger tips. There are days where I have a guitar in my hands for 14 hours and Elixir strings really allow me to play longer without pain or discomfort. Often I'll pick up someone else's guitar and within minutes be feeling the deep ridges of a non-coated set of string. Ouch. OK, I'm a baby. This is also a reason why I prefer polyweb over nanoweb.
Do I have something, anything bad to say about Elixirs? Hmmm, the packaging hurts my eyes. Oh yeah, and that they discontinued the classical guitar sets. They are well aware of my objections.
Elixir Strings Electric Guitar Strings, 6-String, Light NANOWEB Coating