Is this worth using?

Hmm... I'm not a top-tier player myself, so I can't say for sure, but if you want a simple way to gauge performance, you can check if it's included in general use, speed-up decks, true-attack decks, or the 'goat' cat combos. As far as I know, the Ishishin Dragon isn't one of them... ㅜㅜ

Slurp! Isis is powerful against certain enemies thanks to its special effectiveness against super-lifeforms and its wave attack, while Shinryu has a stable attack range against red enemies, hmm! Both will be reliable assets in the early game, but their short range or questionable cost-effectiveness might be an issue, so raise them carefully! Congratulations on obtaining them!

Neither is good. Still, Isis is somewhat usable.

I have both but have never used them... I heard they're pretty much unusable in actual combat.

Neither of them are top-tier though.....

If you don't have any other Ultra Rare units, you can use Isis for now and switch to a better one when you get it.

I heard they're both trash.