Open discover, pick something with a long list of packages, and go ahead and use the side bar to navigate down to say 1/2 to 2/3 and then try scrolling down with the mouse wheel. It will jump back to roughly the place you were in the package list. This is an intermittent bug, I can get this to happen the first time every time I open discover, but if I click away from it on another application and come back to it sometimes it will allow scrolling again and function as expected.  The keyboard navigation not working is not intermittent.  

Reproducible: Sometimes

Steps to Reproduce:
1. Load discover pick long application list e.g., games. 
2. Scroll down half way
3. Attempt to use mouse wheel to scroll through applications and sometimes even side bar. 

Actual Results:  
Scrolling ceases, and it returns you to roughly the same spot in the list of applications as you were with a jerky back and forth motion.  Changing window focus and coming back to it will sometimes resolve the issue. This is initially not intermittent for me, but becomes intermittent with focus change. 

Expected Results:  
Smooth scroll through list first time every time. 

Fairly typical setup. Microsoft mouse connected via USB,  i5-2300, 8MB, Neon 5.8, B75MD3H board, Microsoft 4000 keyboard. 

Keyboard navigation would be nice to add. I normally install things through muon or command line -- so for me its not a major issue, but wanted to check out installing a few things through discover. This might frustrate some new users.  

The new look of discover is great. The old look was like it was designed for a mobile platform (which it probably was). This one may be too, but it looks a ton prettier on the desktop.