Definite enhancement for me. I made the switch after I was cinching down so hard on my clip straps that I couldn't get my foot out of the pedal.
You probably already know the benefits of adding pull to your pedal stroke since you use clips. With clipless you can pull or push anywhere around the circle that you want with full power. You can use different muscle groups when others are burned out - mix things up a bit. To some extent you can do that with clips, but not 100%. When you get your straps tight enough to get that kind of connection with your pedals, then you're stuck unless you reach down to release tension on the strap.
I held out for long time, but nothing like clipless pedals and a very stiff cycling shoe.