Doing things differently can result in two things. Either the result is innovation, or as is the case here, disaster.
The first thing that came to my mind after close to 15 hours of play (spread over a week) when i decided to review it was that Earth was not even remotely like any of those aforementioned games. Sure, starcraft had 3 different races, but they were BALANCED. The reason most rts games avoid having too varied races and units and whatever is that being a competitive game in a competitive genre steeped in the lore of pro gaming, every single side, faction, unit and gameplay element has to be perfectly balanced. It doesn't help to have four races. And when Earth's developers show little talent in balancing even the basic relationship between static defense structures and mobile units, one can only expect the game to go downhill from there. To sum this up, base defenses are to most units what an abrams tank is to a kitten. Defenses are so ridiculously overpowered, relatively cheap, quick to build and so friggin awesome that a whole fleet of T3 units attempting to breach the base will often be destroyed in a matter of seconds. You would think this sort of balance issue would lead people to turtle, and you are right, because the way resources are gathered requires little forethought and precludes expanding. The core of competitive RTS play is expansion, but when one stupid turret can defend a small mining outpost against ranks of units, its pretty much better to just take a small slice of the map pie and amass units like a vacuum acquires dust.
This wouldnt be so bad because the graphics are awesome and the gameplay is fun. Right? Well, right and wrong. The graphics look good, although alot of units are poorly animated and stiff. The command interface is clunky, confusing, and severely lacking. Complexity need not be confusing, as supreme commander demonstrates via its fantastic implementation of a complex UI, but Earth is stuck with this clunky old-fashioned abomination of a toolbar set that wouldnt look out of place in some esoteric science program. Furthermore, while there is the option to change the default left-click order to a blizzard style left-select right order one, right click also rotates the camera, whcih means in the heat of battle one is not giving orders so much as he is fiddling with the camera and seeing the massacre of his troops from funky angles.
Last and probably least, the campaign is the most awkward and laboured experience i have ever experienced in any RTS to date. The story is hogwash, with many parts of the campaign replete with unnecessary sprinklings of crappy dialogue and retarded mission objectives. I would probably have thought better of the game if it eschewed a campaign altogether (like sins of a solar empire) and just went all out for a good single player skirmish experience.
Ultimately, a waste of time. Whatever hype there is or was, don't buy it, unless you have a quirky taste or a high tolerance for poorly made games.