Holy crap...here I'm thinking super rough broom...and there is no finish. :doh: No amount of grinding will make that look better. Gawd...the crap some people put down and call good.:wall::doh:
Only way to fix that is top it, and not with the overlay crap either. The real deal concrete and put a finish on it. You can do a 2" overlay with regular 3000psi concrete with either a 3/8" pea gravel or grade 5 rock...something around 3/8" or smaller. Add a layer of 10ga 6x6 mesh in it as well. That "surface", and I use that term reluctantly, would have to be pressure washed, and a bonding agent applied.
You could also go over it with a 3 1/2"-4" regular concrete mix with much the same prep and same mesh....you just don't need the small rock...and could get away without the bonding agent by drilling in some 3/8" rebar dowels into the surface and bending them over to give the concrete something to grab onto. I'd do that every 2 to 3 feet each direction. That would hold that puppy together.
No doubt, you have a mess that is going to take a lot of work to fix. The above is how I'd recommend to my customers how to fix it. There may be other ways, but IMO, either of these ways would give you the best product.