IMO, the little things add up fast. Syntax highlighting can make things easier to read. Linking ('s and )'s let's you close a conditional without counting the number ('s less the number of )'s. Syntax aware re-factoring let's you safely change all x's to index etc. Built in language support allows you to catch many syntax errors before you hit compile and the help goes on and on.

PS: And don't forget the big things like built in debugger support.