I'm a few chapters into volume 7 and I adore this manga so far. The character writing and story telling have been great so far.
Guts' is a very interesting character, because 99% of the time he's incredibly cold and standoffish, but every now and then he shows that he does care for his comrades and friends. An example of this is when he and Casca tumbled over the cliff and he did everything in his power to keep her from getting hypothermia or sick, even if she wasn't too appreciative of being saved by him, given she utterly despises him so far.
My favorite character so far is definitely griffith (world's least creative opinion, I know). I'm a psych student and griffith to me is an incredibly interesting character. He's an incredibly power-hungry individual, but he puts on this front of being noble. This front isnt even entirely a front, however, as he seems to be genuinely noble at times, no faking or anything (he seems to genuinely respect the princess, and truly cares for his comrades in the band). It's very clear that he is not and clear-cut psycho/sociopath (atleast not yet, given he's part of the Godhand in volume 3), as shown with how he reacted to the child in the band of the hawk's dying. He would never admit it, and he doesn't, but that moment seemed to make it clear to him that his dream is costing people's lives, and now he has to fulfill this dream or all those deaths were for nothing.
Lastly there's also Casca, she has her own interesting internal battles. She hates Guts' because he's so reckless in battle, but she yells at him that she doesn't care if Guts' dies, as long as he doesn't bring down griffith with him. there's clearly some unreciprocated feelings for griffith from Casca, which also explains her envy of how much griffith respects and cares for Guts. I'm hoping that she comes to her senses and stops hating guts' guts (get it? hahahahahahahahahahahahaha[I am the least funny person i know]hahahahahahahah).
Overall incredible story-telling and writing so far, I can't wait to read more!