It's about as tough as Falcon 4.0, which I'd say is fairly complicated. DCS: A-10C is at least as complicated, but if you haven't looked at that the comparison doesn't help much.

I think some things in BMS are a little more complicated and some are less so, when compared to Falcon 4.

I have found it difficult to learn for sure. I've found a few things that have slowed me down in getting up to speed witgh it. It remains to be seen whether they increase my enjoyment and sense of involvement, or become inconveniences.

For example, some of the simplified actions in the original Falcon 4, like using the radio to contact the tower, can't be done as effectively without 'programming' a data cartridge before takeoff. The ICP is more realistic and I'm still struggling to use it to advance steerpoints and change things about. Some things can still be controlled by keyboard shortcuts rather than operating the buttons in the cockpit i suppose, but its a lot to get to grips with.

I'd say its more complex and 'true' than the original F4. My expectation is that the additional time taken to learn this will be worth it.

I'm enjoying the absolute Hell out of this. I think it's really well done. Not impossable to learn , just takes a little time. But , yes, worth it I think. Had some things I didn't get, and asked a few questions. Now I'm killing tanks with Mavericks and taking out SAM sites (One of my favorite targets!). Still screwing up like crazy in the campaign.
I'll do something well in the training missions, and think, "All right, ready for the campaign!" And then completely blow it. Frustrating, but you have to remember that r.l. military pilots train for months to learn this stuff. We want to pick it up in a few minutes. Still can't believe what they did with this old game.