Hey there! I am CAP7A1N, a UI designer with 2 years experience. I am making a menu for an ‘assignment’ based game. Only the framework and animations are done. Please let me know how it looks!
EDIT: Fixed bug brought up by @Craftero - Use the link to see.
I apologize for the video being laggy, this is the best quality I can get. Link below 
Test it (link removed) to see it without my lag.
Scaling may not be the best as this is only ment for computer.
Thanks,
-Cap
Definitey looks great when I look it. The animations were hard to see because of the lag.
I suggest to continue like that
Thanks, I added a link so you can test it without the lag.
Okay so I checked that out. Animations look great. I would also add some content on those tabs and make the text a little bit smaller and more centered from the left side
So far, this looks really awesome. The animations are pretty well done.
The colour and icons match together, and everything looks great.
I would really like to see how is it gonna be once it’s done.
Keep up the great work
Very nice animation style! The UI looks great so far, can’t wait to see what it looks like when it’s done!
The colours, font and style blend together rather well! The animations also give it a lot of depth.
I probably would have done this as white but I think you did really good using the dark grey color has a line separating the buttons from the text. Also what font are you using for the UI?
The current font for the page titles is ROBLOX’s SciFi. Although once the UI is more developed, font may vary depending on usage. (Like buttons may have one, labels another.)
As a starting point, the UI menu is pretty good. The icons are easy to interpret and the animations are fluid, which is fantastic. After spending some time testing the interface however, I’ve come across a bug that I think would be worth bringing to your attention.
The reproducible bug I’ve discovered renders any given button dysfunctional until a different button is clicked. The steps to reproduce the bug are as follows.
Reproduction Steps
Once these steps are followed, the button you attempted to click as the grey highlight was moving across the screen will not function until a different button is clicked first, as demonstrated in the recording below.
It definitely looks smooth! I am assuming you used Tweens?
But yes, it looks pretty good. Lacking a bit of color in my opinion, but I don’t exactly know what kind of game you are making.
Happy coding!
I cant get a full grasp of the size of the UI since I know that this is probably just a test window youre running it in and I can only compare it to the mouse cursor size, but I’d recommend making it slightly smaller overall, It gives me a very zoomed in feel as if I was playing on a low FOV.
tl;dr - scale it down a bit
Other than that, its looking great, keep it up 
Thanks for the feedback and brining the bug to my attention.