The listed points are valid, but they are by far not as easy as the author thinks they are. I don't say they are not improvable, but they are not 'little things' that need to get fixed before new features come in. For example, the jars are large because every closure needs its own class (thank you jvm!). Compile time is high because of type inference. Error messages and stack traces are cryptic, because you do high-level programming but get low-level diagnostics. etc.