Its just my opinion about dynamic languages, so no need to be harsh.
Something that I miss in dynamic languages is IDE support, even if it exists, the "dot" behaviour is likley to be not there.
I mean that thing I like about Java and .Net editors is that you can easily make use of it for a quick dirty tool you need to implement, even though you might not no a thing about where to find which APIs, you hit the "dot" and you get a list of APIs supported by the class.
Now this behaviour is hard to find in dynamic langauge editors (for the reason the language type are dynamic), although you can write quick code using dynamic languages compared to Java or .Net, its not easy as every one says it is.
Either you have to go through the whole documentation to find out what your are looking for or try all possibilities.
Yes, you would have to do this sometimes in languages in .Net or Java (and strongly recommend the you read the documents before your use APIs for the sake of knowing what you will use) but for quick and dirty programs , it just a matter of hitting the "dot", and I would not go through the pain of going through documentation for thsi purpose.
Another case that is frustrating is when you know what your supposed to call but you dont really remember the name of the method to call !, .Net and Java editors do much better here then dynamic laguages.