First off I'm really looking forward to larger maps, however, I have the following concerns...
1. Star density, so far this doesn't appear to be much of an issue, I compared the average distance between stars in Galactic Civilizations II (somewhere between 10-15 tiles) and the average distance between stars in Galactic Civilizations III (somewhere between 10-15 tiles) and if anything there are more stars per tiles in Galactic Civilizations III compared to Galactic Civilizations II so I'm 
.
This however, comes to my second point...
2. Planet density, this appears to be where the issue falls. In Galactic Civilizations II with everything set to abundant there averages somewhere between 2-3 Habitable planets per star with some upwards of 4 and in a rare instance 5 (although 5 is usually because of a mega event) Also zero habitable planet star systems are rare.
So far in Galactic Civilizations III with everything set to abundant there averages somewhere between 1-2 habitable planets per star system with some upwards of 3 and haven't found one yet with 4. Lucky to even see a star system with 5 planet at all. Seems to be many stars with no habitable planets at all.
With that all that being said the maps may be larger, it may even have more stars, however, planets seem to be less than Galactic Civilizations II 
This creates the following issues...
1. Stuck in a corner (see today's dev stream) with no or little options to expand because the nearest habitable planet is 25 plus tiles away :@ sucks to be playing that game.
2. Spread out defenses (which you had it Galactic Civilizations II) however, one should be able to establish some type of safe zone, even on the smallest of Galaxies.
Now, some of this you can excuse as we're in space there are areas of empty space however, it is also a game
Am I the only one with this concern?