This includes things like clarity, good english, explaining at the right level (e.g. you don't keep repeating the same points, you don't explain things that are supposed to be obvious for your intended readers), etc.
We would like to stimulate a critical attitude. So I will also give you points if you take innitiative to learn more about the subject beyond the paper's text, e.g. if the tool presents a tool you could try the tool yourself and do some evaluation. You could compare it with other tools. Even if the paper does not present a tool (or no tool is available) you could also do your own literature study to compare with other approaches.
Are the slides good? If a demo is included, is the demo well prepared? Does it give some add value?
This is about how well you respond to questions or critics from the audience.