My quibble with all of the 24/7 shadow liners is how difficult they are to blend out. These set instantly so if you do want to blend for a softer look, you are left tugging away at your lids quite roughly. On the positive side, these are great, long-wearing shadows on their own and are great as bases for other shadows that crease or need help to show up or both! I loved these like made when I first got them but since then, and since finding the Tarte and Sephora shadow pencils which have all the good qualities and also remain blendable for a minute or so, I haven't been using my UD pencils nearly as much. Having said that, Underground is a great brown pencil with so many uses. It doesn't lean red at all - it's fairly neutral to cool in tone and so it's a shade I can wear quite well on the lid or in the crease or as a "one step and out the door" type product.
I was in love with the UD 24/7 shadow pencils when they first came out because they were SO long-wearing and were multi purpose products that worked as eye shadows, non-creasing and colour enhancing bases for other shadows and also as long lasting eye liners on me (they last better than some of the 24/7 pencil liners on me). Over time, though, I became less and less thrilled with how hard these are to blend out without yanking and tugging on my lids. Rehab is one of the more easy to blend shades and it is a lovely shade of taupe brown. I do enjoy using this pencil but do wish it stayed blendable for more than 1/50th of a second!