The Ancient Rylanor features in the Horus Heresy book series from Black Library and makes a neat appearance in Betrayal. He is an ancient dreadnought of the Emperor's Legion legion and was one of the first entombed so, having served at the Emperors side since the early days. Naturally, this makes him a loyalist only choice for any Emperor's Children force following the onset of Isstvan III: but he is not an HQ selection; rather he is an Elites selection.
His points value is more than a land raider. So is he worth it?
Well, he is a contemptor class dreadnought for a start, which gives him an invulnerable save on top of his already impressive front armour AV=13 rating. Couple this with the Venerable status that forces results on the damage chart to be re-rolled if Rylanor's player so chooses and that makes him a tough nut to crack. But he's not impossible to crack by any means. A well placed melta shot will certainly take care of him with a good roll and lucky re-roll on the damage chart. But if I were playing against him, I'd want to torrent him to death by getting rid of his 3 HPs as soon as possible.
That said, he has a high WS BS and S stat line.and will be a terror in close combat. His ranged Kheres Assault Cannon will also give many opponents pause for thought ... and make Rylanor a greater target to take down quickly.
His final rule (Mantle of Glory) allows a morale check re-roll and benefits loyal Emperor's Children in combat.
But returning to the original question: is he worth the points? To be honest, I think the points would be better spent on an upgraded terminator cataphractii squad. And even then, there'd be points left over. So kudos for including Rylanor, but even with his buffs, he is a little bit too pricey for my tastes (too many points sunk in one gamble) to include in a loyalist Emperor's Children force. If his rules were more a force multiplier or if he were an independant character, then maybe. But as it is, probably not.