One of the biggest, and legitimate, complaints people have voiced was that the scale of ships and combat structures were far too small (they were increased awhile ago). Some have complained about research, after many revisions I like to think that it's cost is at a decent level now.
I wouldn't say most many people dislike the planet setup and economy due to how drastically different it is.
It's to familiarize you with the planets in SoGE. The "Planet Sampling" map is a map where there is no enemy and you own a dozen or two planets, of many different types and sizes.