Star Wars RTS? Your initial thought may be "Yes, please!" But not so fast: It isn't what you were expecting.
The real problem is that they did exactly what they promised: They made a Star Wars RTS out of AoE II. When you really think about that, you may realize that it makes a lot less sense than it seems on the surface. What fans may have been clamoring for in fact was more along the lines of "A Star Wars RTS that is as good for that setting as AoE II was for its historical setting." That's a much less specific desire but one that may have made for a better game.
When you play SW:GB it doesn't take long to figure out that you're playing AoE II with sprite replacement. The sense of scale introduced by lumbering AT-ATs and the scarcely controllable quickness of the Speeder Bikes are necessarily dialed back in order to both fit the engine and maintain balance and presentability. But while the technical limitations of the engine may make these shortcomings understandable, they don't make them forgivable when the end result is a bland gaming experience.
The carefully crafted balance of the different selectable armies in AoE II is tossed aside for a short list of tacked on armies in addition to the obvious Rebellion and Imperial forces. Playing as either of the main factions has its moments of enjoyment, but trying to compete as the Trade Federation ragdolls or the bizarrely included Wookiees whose unit types are pulled from thin air rather than from any existing Star Wars fiction is pointless.
The limitations of the AoE II to Star Wars translation becomes pretty apparent when you see how the designers struggled to include X-Wings and TIE Fighters into a primarily terrestrial-based campaign. Adding as many flying units to the game as they did unbalances a lot of games as building defenses for both ground-based and airborne attacks can be frustrating and when one lucky raid by an opponent can set you up for a long but ultimately futile fight to catch up with your enemy's progress. Other aspects like resource mining is poorly translated as well since it appears almost unchanged from the AoE II incarnation (save for some perfunctory name changes) and after a few rounds you may find yourself thinking, "Why do I need to manually mine Ore when I'm the fracking Empire for Pete's sake?" And such a question would deserve a decent answer; none is provided.
Not to say that Star Wars: Galactic Battlegrounds is all bad. If you can forgive the rough translation issues, on its own there is a relatively decent amount of standard RTS-style fun to be had. After all, this is AoE II with Star Wars sprites so as long as you stick to Rebellion or Imperial forces you can enjoy a few rounds of AoE II without all that annoying realism. That may be worth a dozen hours or so for novelty but don't bother trying to play as Gungans or any of the other cheesy races.
In the end the problem seems to be that the designers never got past the "It's Age of Empires... but Star Wars!" pitch line. The inspiration and dedication to the license seemingly stopped at that point as they didn't seem to try very hard to really bring a sense of the Star Wars universe into the game, thinking two proven entities melded together would equal something twice as good naturally. Unfortunately they didn't account for the limitations or the design focuses of either property and the match ended up being less than perfect.