Seriously, it's the most fun I've had playing an RTS since WoL came out. I'm just going to discuss pvp/ladder, but there's a ton of pve content too like a co-op galactic war for those into that.
But basically, Zerospace is a ton of fun. For those of us who aren't GM, the added QoL and simpler macro makes me feel like I can actually execute all the things that need to be done throughout a match and play at a level above what I'm used to.
It plays and feels a lot like SC2, so a ton of your skills will transfer over, but with a fresh coat of paint and its own identity. The QoL improvements are amazing (like a single tab for all of your unit production and another for all of your buildings, formation movement, easy rally w/ attack move on default). And streamlined macro puts more focus on micro and unit control/positioning.
There are control towers on the map encouraging constant engagement and map control. Those power persistent upgrades you can choose from, which might differ each match. You have top bar abilities, giving you more strategic and combat options. Upgrade paths branch (e.g. zergling-like units can be upgraded to either jump cliffs or go invisible in tall grass, but you can't have both).
All of this adds up to matches that are really action-packed, but a lot less stressful to play (personally). I find myself less anxious laddering and having a lot more fun.
I'm just a fan that loves the game, and I highly recommend it. And I really think this is the most promising spiritual successor to SC2 that we'll see for a very long time, and I'm sure a big part of the SC2 community would love it.