It may appear slow from gameplay trailers, but I assure you it's not. I think Man was even being lenient on the average game duration. Many games are over in less than 5 minutes. Goo rush is an incredibly effective strategy.
This is coming from a person who played Starcraft2 ranked and achieved Diamond for a time. The game unfolds very quickly, even faster than Starcraft did, but its design is much more centered around strategy and out maneuvering your opponent than micromanagement and build orders.