I was just given a bottle of this shit - Anyone know anything about it?

It looks very similar to the bio Biz products -

Heya , i do believe you will find some shit in it , fish presumably , and from the bottle looks good stuff , many makes out there now maxicrop , vitax , chase etc .

I have used seaweed before.

Maxicrop

Had powdered stuff, and also liquidised stuff.

Dont really rate it to be honest, although others do.

No I have not used that one. I use Maxicrop.
Seaweed stimulates the micro-herd, gives them a good feed. Happy micro-herd = happy compost = happy plant.
I'd never start a grow without my trusty bottle of maxicrop somewhere at hand! Its an excellent foliar spary too, because leaves carry a microbial load that needs feeding and stimulating just as much.