Daydream Experience Concerns
One of the major concerns for any Daydream experience is the limited number of inputs. You only have 2 buttons and one touch pad. All but one button is immediately taken up if you decide to use the built in object manipulation. The controller is also setup so that one button players will need to use can destroy an entire experience. Holding the menu button resets the controller and headset, which you'll need to do, while pushing it once takes you to the main Daydream screen. If they return to the menu, players will almost certainly need a test runner to step in and tell them how to get back into the experience.
Another major concern is the fact that the controller has 3 DOF that is based entirely on an internal gyroscope. This means the controller and headset will desync no matter what you do. This also makes it harder to get someone in that other main stream VR systems. This makes it harder for players to first step in since many expect that level of control. The fact that the player can't see where there fingers are and gets no reaction inside the space to their placement makes it hard to get players to figure out what buttons they are pushing.