There are a few criticisms that show up repeatedly in the community. Probably the most notorious and most-discussed criticism is the lack of generics. This leads to repeated code to handle different data types. Interfaces can be used to some extent to alleviate this problem. We might see generics in a future release, as the authors have shown openness to generics, but they did not rush through an important design decision.
The next criticism often heard is the lack of exceptions. The developer must explicitly handle or ignore each error. Personally, I found this to be a refreshing change. It's not really that much more work, and you have full control over the code flow. Sometimes with exceptions you are not positive ...
