There's a fair bit of info on the web about it. CDI is better where you need higher voltages to get a spark. It's used in small engines and 2 strokes where fouling can be an issue and also in some high CR or high boost engines where getting a spark can be an issue.

The down side is the spark duration is shorter so it's not as good for lean burn or cruise conditions.

Edit: CDI is better for starting with low battery voltage compared to a standard Kettering system although many electronic ignitions have compensation.