Even if you painted it, first you would need to clean it. We use about 3 gallons of hot water, 2 cups of bleach, 1/2 cup of TSP and a dash of liquid soap, like Dawn. Put it on the surface, scrub with a stiff brush/broom. Let it sit about 15 minutes, then rinse off. (Check how it looks. You may need to do it twice.) Then you'll be able to see what you've really got. The existing paint on the risers might look fine when cleaned. Cosmetically, I think you need to put a brick in where the one is missing. I'd also scrape the extra mortar off other repairs as best as I could, and get a bit of concrete stain to try to darken the mortar on previous repairs.

Thanks guys! Painted it grey like you suggested Keitha and used the bleach mixture you suggested nwduck to clean it. Here is how it came out:

Much better!

So nice!

Looks great!