I never understood the criticism of Geralt as being wooden or a Mary Sue, he's got a rather iconic personality in my mind, I mean for a monster hunter what kind of personality do you expect? Giddy and wide-eyed and jumping around all excited like? I think the best part about The Witcher games is how you can influence Geralt's personality with your choices, you can be downright altruistic in helping people whether they pay or not, a selfish greedbag who does nothing without some sort of gain, or become a monster yourself and just let "innocent" people die. I also love Geralt's sense of humor, you'll probably never hear him laugh but there's a sense of mirth and wry amusement he finds in many situations that I love, it's a very subtle kind of thing and I think this is where his personality excels. The developers intentionally went with the "less is more" rule (though the original author can also be credited for this) and it works well, I also find his voice actor to be very good at delivering, he hits all the right notes and really feels grounded in this world.