I've been playing guitar for over 25 years and in my opinion, these are the best strings money can buy!
The sealed packet keeps the strings mint unlike lower quality strings in paper bags getting oxodised.
Even when on the guitar for a long time, they don't turn green and sound horribly dull like a LOT of other string brands out there. I've tried a lot over the years and always, ALWAYS come back to D'Addario!
These are beautifully bright with a crisp low end, and are very comfortable to play.
This is personal preference to a point, but some other brand strings I find feel too grippy or too greasy (those plastic coated, dull and slimey type - yuck) or don't bend without ripping your fingers off -- and this is nothing to do with gauge or guitar the strings are on, or bad playing habits in these cases.
These are simply great feeling and sounding strings. I play fingerstyle/tapping and these are ideal for that - every subtle harmonic shines through, but these would be great for any playing style.
They stretch to perfection almost immediately so no almost going out of tune once tightened and tuned initially.
Each string has a colour-coded end (and a key on the packet) so it's immediately clear which string is which, so that's a nice touch.
To top all that off, the price is excellent! Crazy good value!