Keep in mind that this is a severely cut-down version of VBS2. I also would assume it's an older version (I haven't messed with this particular 'project' in some time, though, so I could be mistaken) on top of that.
Note that it will not have any of the following features, IIRC:
- Offline mission editor (OME) <--- The 3d editor of VBS2
- Realtime mission editor (RTE) <--- Same thing, but while the mission is in progress
- After-Action Review module (AAR) <--- Fantastic feature, basically what it sounds like (note that I could be wrong on this particular one, but if they stripped the OME/RTE, it would stand to reason that AAR is gone as well, as it uses much of the same framework)
Also note that it's basically the ArmA1 engine, without many of the nice things you find in A2.
Still, it's free, and it has UK gear. Can't argue that much with free, just be aware that what you're getting in this is quite a bit different compared to the full, current military version of the software.
Star Citizen is an upcoming persistent-universe space simulator being created by Chris Roberts (veteran of the Wing Commander...