My opinion:
So I started my osu! journey on lazer (before it was ranked, as well) and it was pretty great.
But, now that I moved to stable (yes, I went backwards)... I can't go back to lazer.
It's not the interface that puts me off, I actually like how lazer looks right now (but I really don't like the new interface that hasn't come in yet)
In lazer, my cursor movement feels a lot smoother (bad) and that it is lagging behind slightly. I'm a mouse player so I don't really know how it compares to smoothing in tablet drivers, but it feels wrong to me. I think it might be a performance issue, but I'm not totally sure.
I also have this weird issue where sometimes it will randomly change my offset and make me start tapping late. Restarting the game seems to work.
Lazer also has an issue when where I'm using screen scaling, the mouse sensitivity setting doesn't work the same as stable. I have asked about this on github.
Also, lazer has far worse performance in conjunction with overlays, if you care about that kind of thing. (It's unplayable for me!)
So, while lazer has many benefits, there are just a few remaining issues that make me not want to switch back to it, even if that was how I started playing the game.
(and yes, i know opinions from relatively new 6 digits don't really matter!)