Still don't like him though.

As a teen he was, not sure about adult James.

Member of the Order, died trying to buy his wife and son time to escape...

Well, he was an immature teen but he was a brave adult and loyal husband and father, as it is implied.

Lily wouldn't have married him if he hadn't changed.

He was an immature teen but he changed.

His teen years, yeah. Nothing's really been known about his past adult life except Sirius's words.

He died to protect his wife and child , perhaps he once acted up but Snape wasn't any better

Ok, he was an immature bully, but then he changed.

Being honest we know very little about James' personality, but it's unfair to reduce a whole person to just one trait.

He was barely even a bully, it's canon that Snape's group of friends were just as bad to them, it was a bitter rivalry. (I guess you could argue that since Remus said it, it might not be, but Remus is far more mature than that, he need not lie about something like that.)

James Potter was kind and loyal to his friends, he died trying to protect his family against the most powerful dark wizard of their time without a wand. Hey may have been immature as a kid sometimes but he was such a good and brave person, he literally spent 5 years learning to become an anamagi so his friend could get through an awful experience better.

I'll defend James to the end, he bloody deserves it.

Was was a bit as a teenager.

He was a bully and grew out of it.

Being a bully in your younger years does not define your entire life. If James was nothing more than a bully, than the same argument could be made for Malfoy, Snape, Lucius, etc.

A big theme in the series is that characters can't be summed up that simply.