You might be wondering how C4.5 is different than other decision tree systems?
First, C4.5 uses information gain when generating the decision tree.
Second, although other systems also incorporate pruning, C4.5 uses a single-pass pruning process to mitigate over-fitting. Pruning results in many improvements.
Third, C4.5 can work with both continuous and discrete data. My understanding is it does this by specifying ranges or thresholds for continuous data thus turning continuous data into discrete data.
Finally, incomplete data is dealt with in its own ways.