Here is my feedback for the duration of the E3 Demo:

Overall the game is fun but I'm skeptical about my motivation on the long term. At least with the customization you'll get kind of a progression (hopefully).
I won't get too deep into things I have read more often here on the Forum.

The colors of the UI must be adjusted or customizable, speaking of the shooting arrow which I have read about on this forum quite often. But this applies to more situations. For instance the Pass-Symbol. The fan-screen as well. I often could'nt read the number because of the colors of the seats.

The HUD element that shows you the current rounds feels useless if you have the stripes on the arena itself.

Dodging needs to be nerfed a little. Especially if you dodge on the edge of the arena you can get yourself on a high place the others can't follow and you can accelerate to an incredible speed.

There needs to be an afk-kick. There are already bots in there you can at least work with. But if a Player was afk, you had one less player for the whole match.

Now on the Positives:
The rollerblades, the momentunm, the speed and the steering felt good.

If you tackle simultaneously with an enemy, both you and the enemey gets knocked down.

The passes don't work magically if you press the button, you have to consider your positioning, the range and the momentum of your companion (to a certain amount)

The overall passing mechanic is a good idea so you cant just pass all the time but you have to ask for it or do it manually.

the music is cool

by holding the throwing button you charge up the power. Flicks on the long distance of the arena will be a thing. Charging up the throw will give you strategiv opportunities.

a dunking animation would feel awesome if you manage to touch the gate + would look cool in the replay.

different angles the ball can be thrown into the arena

as one team starts on the same side as the ball spawns, a countdown of (maybe) one minute until the gate opens would be a solution. The first one minute of the match would be a battle for the ball possession and give both teams the opportunity to get the ball.

Maybe variation in the music genre with differend arenas?