To make a general statement, they are just as good as their photography counter-parts. Most recent cinema lenses are based on models used for photography with some modification to improve them when used for videography.
Taking Samyang as an example, they often have pairs of lenses based on the same optical design. The main difference is that the body of the lens is fitted with gears so that they can be driven smoothly by a motor. The issue which arrises when using these lenses for photography is that the rings rotate smoothly and have much more throw. So when focusing (or zooming when applicable), you must turn the ring much more to change the focus distance than you would with a photography lens.
The aperture ring also rotates without clicking, so you must be attention to when it actually changes. This could be an annoyance if changing aperture often. Cinema lenses are labeled with T-stops which is a more uniform scale for light transmission but usually close to what an F-stop is.
Finally, sometimes the optical formulation changes, although this is unlikely to reduce image quality. The difference is that elements are made so that during focusing, focal-length stays constant and during zooming, the focus distance stays the same which may or may not be the case for the photo lens. Look for the term parfocal if you want to know more.
Now, if you were to shoot photography only, there should be little reason to cumber yourself with any of these issues. If you do both photography and videography, it's up to you to decide if you prefer to have minor issues during photo sessions or video sessions! The big difference between photo and video is that what happens while manipulating the lens gets recorded in video but is unnoticed for photos since it happens between shots and not during.