Good game. Bad science.
Others have already mentioned that this is a good near-future science-fiction setting, and it is. One of the very best near-future SF games in fact, despite the fact that its timeline is the result of an in-house wargame played by the original developers at GDW, rather than any sort of reasoned forecasting (the dev who played the French won the campaign, hence an Earth dominated by French interests in 2320).
As above, my great complaint with 2320 is that the publishers decided to stick with the long-abandoned stellar data (which dates back to circa 1966) used in the original Traveller 2300, instead of upgrading the science along with the game.
The stated reason for retaining the obsolete astronomical data is the desire to keep 2320 AD in line with the game lore from 2300 AD. This is a fair call to make; unfortunately for me, it makes the setting very difficult to use as a plausible "near future hard SF" setting.
I'm no astronomer, nor am I a science hardcore, but even I know, for example, that Alpha Centauri is a radiation-soaked hellhole of a star system, unlikely to be anybody's idea of a viable colonial hub. A space station waypoint, or "jumping off point", sure -- but even terraformers would be simply making work for themselves trying to engineer a liveable biosphere in this particular star system.
Again, I'm merely a very casual astronomy fan, not a science hardcore. The truth about the current state of Alpha Centauri is a Google away. I started websurfing for current details on the key star systems in 2320 AD to help flesh out what I might tell players, only to find that the 2320 versions of these places don't even jibe with what little we know of them today.
Author Colin Dunn has done some great work with 2320 AD, but I can't shake the feeling his talent would've been better used if he'd been allowed to use current stellar data, such as the Hipparcos data, or even the stuff the Hubble telescope is providing every month like clockwork.
The fun of a near-future, so-called "hard-SF" game setting is the sense of plausibity it brings to one's game adventures. Sure, even the term "hard SF" is such a complete oxymoron, it borders on an outright lie, but you take my point. True or false, it makes the game events feel more "real" for the players.
2320 AD is probably the best game setting out there of its kind, but if its "re-imagining" had included updated astronomical details, it would have had more to offer the current generation of gamers.
Excellent work which falls one step too short.