You save quite some money buying them in packs of three sets.
I don't use this strings anymore, I went to 11s, cause these were way too thin and also sounded too bright for my taste.
I did stick to the brand though, and I use D'addario stings on most of my guitars - I trust their quality, and another great thing is they are available anywhere, if you're on the road and a string breaks.
Since they're so thin, it's important to carefully pull and stretch them when you're winding them, so that you get better tuning stability and a bit higher tension.