I have over 500+ hours of it, and i have ranked high on the ladder.

Let me explain why i think unit variety is fine. You have more than enough units to cover all the roles you ever need from light to medium and heavy support units all with their little own type of micro, the problem with the game lies in the upgrade system. There are a couple examples of cool upgrades in the game in units such as the lancer and beta stalker that change weapons and role with said upgrade's. The problem is that these upgrades all have the same cost and most of them are relatively useless and underused, so you endup with a game where massing 1 or 2 unit types with some races is the best viable strategy.

Also pacing isnt an issue but more the lack of choice and different viable openers like economy opener, rush allin, balanced start, grey goo doesnt have any of this, instead it has the same boring openers that you repeat from matchup to matchup or even from map to map. Since everyone expects these openers the game devolves into a quick 5 minute match or a 50+ minutes slug fest most of the times, there isnt any kind of balanced games anymore.

In a nutshell grey goo is a great concept, but so badly executed, its like the framework for a great game is in there, but every balance decision and the presence of broken systems such as the upgrades really make the game not recomendable.

Like homeworld deserts of kharak has less units and a super simplified economy and building system but provides a better multiplayer experience than grey goo.

Even act of agression with its super complex and sometimes confusing tech tree and massive unit counts is a much better game because the core gameplay loop is fun. Grey goo doesnt get build variety right, it doesnt have any kind of balanced openers, your just massing 1 unit type versus another and hoping you break your oponent eventually.

Its a game thats fun for the first 20 hours, after that you truly start seeing how truly broken and flawed the game is.