One thing I like: Variation in shots. Angle, focus (as in what's the key feature), depth (close-up, showing some background, etc)... If every shot is the same it can make it a lot less interesting. In my
"Skirmish" mini-story experiment,* because it was short I tried to make sure every panel was different from the last to get the most out of it. Even when you've got a lot of dialogue, a "talking heads" scene can still be visually interesting if you mix up the shots with close-ups on the guy talking, wide angles of the whole room/setting, medium shots just fitting in the people in the conversation... Just look at all the different cuts in a TV show when there's a conversation scene, or for an even better example look at how a good comicbook will do it. I'm a huge comics fan so the more reading a dio-story is like reading a comic, the more I'll like it.
*Feedback/criticism still more than welcome!
One thing I hate: Bad writing. I'm not talking about poor characterisation, plot holes, etc.; I mean spelling mistakes, poor grammar, inappropriate punctuation. It really breaks the flow and reduces the enjoyment of the reading experience when I have to work out what someone meant to say, or there are just little errors that catch my eye. Getting someone who you know has a good standard of written English to proofread your script is a very good idea, or even if you know you're good yourself it could still be beneficial to leave it for a day and then reread it as you're more likely to pick up on any small mistakes. It would probably be good to get it proofread after it's in actual strip-form, to catch mistakes but also to make sure it flows well from speech bubble to bubble and panel to panel, although going back to make any changes is likely going to be fairly awkward at this point!
I have other opinions on what I do and don't like when reading a dio-story but these were the only ones I could think of right now that other's haven't really gone into. I may come back...