The mouse is overpowered... but only compared to the joystick and probably only if you're more used to flying games with M&KB over a HOTAS.
Even then, certain moves are much easier than others, depending on which ship you're flying, which control system you're using *and* whether you have all that FCS/Coupling stuff enabled or not.
So far Waves 1-5 have taken me anything from about 20 to 90 minutes to reach, depending on stuff. An Aurora on joystick is great to start with, but I quickly found myself battling to keep it flying straight, with only the one canon operable. I wasn't even sure all the damage was registering - I could see the Scythe flashing and taking hits, but the damage score wasn't coming up.
Personally, I find the whole Newtonian physics thing a very admirable achievement, but very clunky and counter-productive to gameplay. The learning curve is immense and it's going to take a good few months before I'm a good enough pilot to even play well enough that basic level missions become fun... and that's the key, here - I am playing a game. It should be fun. It is not.
This is a space-sim. I should feel like I'm a ****-hot space ace fighter pilot.
Instead, I feel like a complete Novice playing a complicated Flight-Sim.
IIRC, Elite Frontiers tried this same approach and about 90% of their player base just dropped it. Freelancer went the other way and, while I love it to bits (I still play it online very regularly), it is very Arcadey. Starlancer was far superior in many respects.
SC is almost starting to feel like a game with mechanics designed to justify the Flight-Sim types dropping insane money on Warthogs.