I'm currently level 8 now and overwhelmed with missions after unlocking each wing in the base so that'll keep me busy for a while. There is certainly a lot more here than I originally expected and so much to do - I've got a good balance between side missions, main missions, encounters and other bonus things and as many missions that are playable are for high levels for me right now; seems you are forced to play the secondary/side missions which is great and deters people from racing through the main story. I'm adjusting well to the user interface now and the looting aspect is pretty fun. I'm still rolling with a level 3 AK47 which I've heavily modded so I really need to sort that out next.
Brilliant game so far.