There is a world of difference between allowing your colleague in the left seat to fly you into a mountain and letting him have both barrels because you didnīt get on. It is a fact of life that we are all different and somebody you may love to fly with is not liked by somebody else and viceversa. I would encourage you to absolutely speak up if safety is compromised I would also say, however, bid your time and learn to deal with the small personality frictions that happen. It is not easy being an good FO but you will find and get quite good at different strategies to deal with difficult captains (and despachers, controlers, cabin crew, your pregnant wife... actually I never did master that last one).
I would bring it up by pointing out your low experience and saying that you feel unconfortable and rushed, would he give you a little more time while you adapt to the aeroplane. The problem of giving him both barrels is that when the **** flyies it tends to splatter everybody.
Look at it as a challenge, in due course you will also find yourself flying with the opposite: a captain for who anything YOU do is too racy. It will be a different customer to please but heyho that is life as an FO.