This patio had an issue with standing water. Since concrete is impervious to water it would pool up in the center and never really drain. This made the patio not only unsafe, but also the perfect mosquito breeding ground.
The builder made a really nice patio for the family, but the concrete guy graded it the wrong way, so instead of water running off it, it makes a big puddle in the middle.
Rather than an overlay or re-do, we cut trenches then installed a drain pipe, ground and polished concrete between score lines, finishing it off with dye and densifier.
To introduce an element of polished concrete with the aggregate exposed creates a decorative and functional element on the patio.