Readie - 3:43 pm on May 31, 2013 (gmt 0)
I've used plugins and written my own numerous times.
The advantage of using a third party plugin is it takes less of your time.
The advantage of writing your own is you can tailor it specifically to your own needs. The same logic applies for pretty much any JS plugin.
As far as writing your own slideshow - with a working knowledge of the overflow and position CSS attributes, it's pretty simple.
For example, to slide an image in from the left, you would place it in a fixed height/width div with overflow:hidden and position:relative.
The image itself would be position:absolute, and it's left would be set to negative [image width].
You could then call jQuery animate on it like so: