The AI in BH&H is far and away better than Phase 2. I flew one mission in Phase 2 in a DrI and came home with seven kills, expended 778 rounds with a 44% hit/miss ratio. In BH&H, I'm lucky to make it home alive. The AI is not invincible, but it makes you work for your kills. I've had my a$$ handed to me by the AI on numerous occasions. There again, I've come up against rookies and it ends up being a turkey shoot. You never know who you're up against until you're in the thick of it. In the original release the AI wasn't much better than Phase 2, but install the latest patch and look out. They'll hunt you.
The system requirements are a little higher than for Phase 2 but not much. You can find all of that info here....
http://www.overflandersfields.com/
CJ