One of the major issues with slides is that too often they are designed to be usable without the presentation. Often times they are emailed to people who were not in attendance.
You end up in the worst of both worlds: a presentation where the presenter is nearly irrelevant (I can read slides too) and notes that are spread across too many slides to be useful.
It takes extra work, but developing one slide set for presentation and another set of materials (not necessarily slides) for reference works 1000x better.
An article or other write-up is a better "leave behind" alternative. You can include all of the points you made that were not on the slides and even a FAQ to substitute for audience questions.
You end up in the worst of both worlds: a presentation where the presenter is nearly irrelevant (I can read slides too) and notes that are spread across too many slides to be useful.
It takes extra work, but developing one slide set for presentation and another set of materials (not necessarily slides) for reference works 1000x better.