the short answer is that the lasers are well underpowered - but still strong enough to wipe out your eyeballs and come with zero protective measures.
It'll probably cut thin card and mark wood and bamboo works well.
And leather.

The milling/cnc is equivalent to a cheap knockoff dremel.
And will make a helluva mess.

But yeah it'll engrave and do small carving on wood.
Not sure I'd try metal - just one bit of kerf could bugger up the printer quite easily.

basically if you're not paying more than £100 more than an equivalent non all-in-one 3d printer it's worth it.
otherwise, save up and get a k40 co2 laser and make yourself a cnc with the 3d printer.

Speed wise - lol, slower than 3d printing.