Well, the card is can't be easily classified into good or bad or awesome. Like many cards, it's situational. It's effect only works in some cases(thank you, Kaizen).
Well, the most popular decks right now are:
Blackwing Varients, which are all dark and Catastor is useless against, 0:1
Lightsworns, which are all light and Catastor can face them, 1:1
Gladiator Beasts, works against all I think, 2:1
Plants, works against them, 3:1
Dark Skill Drain, doesn't work against it at all, 3:2
Zombie Varients, doesn't work against it either, 3:3
Norleras Varients, fails, 3:4
Chaos Varients, depends, and even though CS is Dark, it has an effect that can RFG Catastor, but at the same time, half of the monsters are Dark-attributed, so it's pretty neutral.
Basically, it bearly works against any Skill Drain build.
Ok, from some of the popular decks I've listed, Catastor works against 3/7 of the decks and doesn't against 4/7. (of course this is just an estimate, there are still more decks)
I'd like to note that Catastor isn't broken at all, it's effect doesn't work against the most popular attribute, Dark. Neither does it work in this meta as it would of in others, because of the popularity of Skill Drain. Catastor's effect is pretty balanced in this meta, IMO. If a new ban list comes out any time soon, changing the meta into something that Catastor would be more useful in, it would be limited or banned, which is pretty far off IMO.
As Kaizen said, there are lots of S/T that can stop, like BTH, with Solemn limited it's hard to avoid any of em'.