Got this mount for my 2014 Moto X. I do not use a phone case. Out of three or four mounts I tried at Best Buy, this one seemed to grab my phone best/with the least effort and was actually also the least expensive so I am satisfied with it. I use the suction cup mounted to my windshield, which also has been fine so far (about 4 weeks) and has not shown any loss of suction due to heat or vibrations/bumps. The mount does cover the volume buttons on my phone (on the side), which may annoy some users but has not been an issue for me since I connect my phone to the car via bluetooth if I want to use it for music/phone/GPS while driving. This way I can change the car volume instead. As someone who occasionally enjoys a fast turn, I can say the ball joint pivot of the mount seems adequately stationary when tightened, and this was important to me when choosing a mount. I imagine this mount could accommodate any current smartphone, potentially with the exception of a Galaxy Note or iPhone 6 Plus, but even those might be okay. In addition to gripping from the sides, the mount also has small fold-out ledges on the bottom, so it is unlikely a phone would fall out unless the side grips have poor contact with your phone and you hit a large bump.
I will note two negatives I have found to this mount: 1) I have also used an iPhone 6 with a hard plastic rounded case, and while the mount still works, it does not grip this phone as well. 2) The release mechanism for the mount does have a cheap feel to it, and I am not sure how long it will last before some plastic part breaks.
I have to select yes or no for whether I would recommend this to a friend, but really I would recommend it to a friend *depending on their phone* and would suggest if possible that they try it in store first.