Legionnaire was the only rpg book released in that universe, IIRC. Everything else is miniatures wargames on hex maps like Battletech. If you google it (I did a while back) there's still a following, and you can find things like map generators and such.
Still, for a main book I thought it did an awesome job standalone.
As for mechanics, well, they get the job done. Not too complex. You have your target number you want to roll under, and you roll d10s. If you're unskilled or it's a particularly hard task, you roll more dice, thus making it more difficult to stay under the TN ceiling...
You could tweak it either way (more or less complex), it all depends on preference. Though I did think the starship navigation systems and hyperspace was fairly well done.
All in all, I thought Legionnaire was good as is.