You know what? It's fine. Very good for a first game. I'm sure I couldn't have pulled off an endless game when I started, so big props for that. You even save/reload the high score between page reloads which is a nice touch.
It still looks a bit placeholder-ish (simple geometrical shapes, solid-coloured) which is probably fine for this game but could be further improved. The menu background is also quite close to the default Unity blue and the sliders in options are as default as they get. Try changing the font and use a different image in your future games, so it is "less recognizable".
And having a Quit button is pointless in a WebGL game, since it does nothing at all. Some developers circumvent this "flaw" by freezing the game or by loading a full-black screen. *Don't* do this either, please – if people want to close a WebGL game, they just close the tab. You can just delete the button or disable it in WebGL only, with something like:
if (Application.platform == RuntimePlatform.WebGLPlayer) gameObject.SetActive(false);
As for the gameplay, I would love to be able to control the ball with the mouse. Arrow keys and WASD are fine, but this game requires precision and "Mouse X" axis would allow you to slow down/speed up as much as you wanted. Or you could simplify your controls by simply making the ball's "x" position equal to mouse's "x" position at all times.
Also, if you had slightly more time before landing (= if the jump arch was higher), you could have more elaborate obstacles. Now all you have time for is avoiding a spike and the best strategy is to limit your movement to a minimum and stay close to the center (at least that's what I found out). You could also add collectables and alternative paths if you want (e.g. a simple path to the left, or a "difficult detour" with a collectable +10 points to the right).
But that's probably making the game more complex than it has to be. I'm just looking for ways to motivate players to press further, as that becomes a problem in endless games once you stop introducing new elements.
As for motivation, did you know Newgrounds has a public scoreboard? Competing with other players for the highest score is much more fun than trying to beat your own high score.
https://bitbucket.org/newgrounds/newgrounds.io-for-unity-c/
http://www.newgrounds.io/help/components/#scoreboard
You can shoot me a PM if you need help setting it up if you decide to use it in this or a future game.
Two bugs I encountered, the latter occasionally froze the game on (re)start.
– Falling pad (missing script):
The referenced script on this Behaviour (Game Object 'falling Pad (2)') is missing!
– Restart bug:
"A script behaviour (probably UnityEngine.Audio.AudioSpatializerMicrosoft?) has a different serialization layout when loading. (Read 32 bytes but expected 36 bytes)
Did you #ifdef UNITY_EDITOR a section of your serialized properties in any of your scripts?"
Welcome to Newgrounds and good luck with your future projects! :)