What I dislike (hate's a strong word XD) working alone:
It's fun to work and bounce ideas off other people.
The entire onus of work is on me.
We're our own worst critic, but without outside eyes, we can also miss our mistakes.
Sometimes it'd be nice to have a McCartney to my Lennon (er...maybe that's a bad analogy, Ringo was my fav.)
Things I love/like about working alone:
I am in charge of when I get a script! No more waiting around for someone else, if I'm waiting, it's my fault.
I don't have to worry about being, you know, halfway done with a comic and then the other person suddenly decides they aren't interested anymore and I'm left holding this comic I'm having fun working on and I can't finish because my partner bailed. Yeah...it happened before.
Sense of pride/accomplishment.
Since I'm doing it all, I feel I'm benefiting from what improvements I'm making. I guess I mean, I'm doing more work than if the work was split, so if practice makes perfect, then I'm getting in some good practice doing it all (though I'm sure a partner would help me improve, too.)