TL;DR
The icons in 2.0.18 [experimental] look REALLY wonky, and should be changed to be less... modern corporate logo-y.What?
I'm going to tear through these piece by piece, because I don't want to be too vague/miss anything in the effort of being concise."If I Had More Time, I Would Have Written a Shorter Letter."
First, the old vs. new:
I'll skip mentioning any icons that were literally just scaled up because I think those are all fine.
ALT Mode: I guess it's fine, it just feels weirdly blocky compared to the rest, somehow. Id live with it though!
Blueprint/Planner/Book icons: The center icons should have less dead space between the dotted square to match the smaller versions. Book looks cool.
Import: Looks better as it does honestly, I like it.
Roboport: I feel like I liked the lightning more, but no issues here.
Copper wire: DEFINITELY needs to be colored copper. I couldn't tell what this was until I hovered over it. Additionally, if red/green are going to be as they are, the copper should match as a 'C' for consistency. [and copper]
Red/Green cable: Strikes me as weird and too modernized, but I guess it's consistent.
Artillery strike: I thought this was a mining drill at first. I think it would do much better if the shell icon closely resembled the real deal, color or otherwise..
Discharge: yeah. I get it. It's nothing crazy, i feel like colors would be nicer here but sure yeah.
Spider remote: I don't want a dang spider in my quickbar! eek! get it out of here! No, really, I think it gets the message across but I think having a spider there is just bleh. If not for me, perhaps for others. Not the end of the world if it stays but I'd prefer it to be literally anything without a spider on it. I get it's rough to convey its point without it, but like, bleh