It really depends on your play style. I love to run skrox units. I almost always take them. I look at the unit as a Kroxigor delivery unit. A way to protect the Kroxigors and get them into combat. 8th edition removed the rule allowing the Kroxigor to be attacked in the second rank. The monstrous infantry rule made it possible for the Kroxigors to get full attacks from the second rank. Couple this with added Kroxigors giving the unit the Fear rule and you have a very nice unit. It does come in kind of expensive though (55pts per Kroxigor plus 8 skinks per Krox). The minimal unit size I take is about 20 skinks and 2 kroxigors. If I am taking a lot, I will make the unit about 55 skinks and 3 (or 4) Kroxigors. The skrox unit is an excellent flanking unit and moves very fast across the field.
I think they are fantastic personally. I see alot of elite infantry and knights in my meta and vs those sorts of troops Skinks and Saurus die the same. So for half the points i like to have skinks soaking up the hits. The Kroxigors also work as great can openers vs knights and dealing with monsters, as a unique unit they can't be thunderstomped/stomped. I run 30 skinks, 3 krox usually and its works out pretty well. Template attacks on those blocks though can decimate bodies with T2. I haven't played with it much but lore of light I think would work wonders with skrox units. giving the skinks WS 10 and pha's protection will make the enemy need 6's to hit which will almost always end in combat going your way.