If your cabinet boxes are solid and you like the layout, painting is the best-value kitchen update there is. Replacing cabinets can cost many times more than refinishing the ones you already have.
The catch is prep. Kitchen cabinets are coated in years of cooking grease, and most have a glossy factory finish. Paint put straight over either will chip and peel. Proper cabinet painting means degreasing, sanding, and using a bonding primer before any color goes on.
Removing the doors and drawer fronts and painting them flat gives a smoother finish with fewer drips. The boxes are painted in place with the counters, floors, and appliances masked off.
Cabinet painting isn't the right choice when the boxes are water-damaged, swollen, or falling apart. In that case, a good painter will tell you so instead of painting over the problem.