It isn't really. Its researchable ability is somewhat useful as it allows you to destroy focus fired targets quicker, but for the most part you will use few if any of them.

I love the Cielo.  All you need is about 5-10, but the abilities are useful, even the embolden one.

Cielo looks so cool. I love how it looks. But I have only seen it in screen shots.

 Its good, just like having enough Hushiko's is good they can make a fleet ridiculously survivable, and makes it so you'd be better to focus on the Hushiko's. I play Advent, so subjugators are alright but I like the Hushiko's.

Cost-benefit, my good man.  Kodiaks shred things on their own; Hoshikos permit them to survive long enough to do so (both by healing them and by shutting down enemy units, in certain circumstances).  Cielos help your existing units shred things a little faster, which, if you think about it, is just like adding another few combat ships, regardless.  So, if you think about it, either way you're just improving the stopping power of your fleet.

Now, if Embolden provided a boost to ANTIMATTER regen instead of RoF, you'd be in business.  The possibility gets me excited just thinking about it.

man i hope the devs pimp the cielo's weapon from laser to autocannons just like the pirate cutthroats aka cielo with spikes