Ricardo blogs about the differences between C# and VB.NET. Well, I'll give you one, which is very harmful in some areas.
Class C is a derived class from DataTable. DataTable implements ISerializable, but does this private. Class C has a new member variable which has to be serialized as well. Simply adding '[Serializable]' to Class C doesn't work, because a base class already implements ISerializable. So C has to implement ISerializable too.
Because DataTable implements ISerializable private (ISerializable.GetObjectData() is private), this can be a problem, since I have to do the complete serialization of C and the data in its base class by hand. Dino Esposito wrote an article about that, it's located here.
Using Dino's article, I can implement ISerializable and the GetObjectData() code to serialize the data and the private membervariable of C. That is... in C#. In VB.NET you can't, because the VB.NET compiler will throw an error that a base class of C already implements ISerializable. There is no way in VB.NET to re-implement ISerializable or to make the serialization formatter call a GetObjectData() method defined in C to do the serialization, simply because it will see the GetObjectData() method of DataTable as the implementation of ISerializable.GetObjectData(), which will serialize the DataTable contents, but not private member variables of derived classes.
Now, it took me some time to work around this (create a C# class with the member variable, derive the VB.NET class from that class) and it still isn't a solution which will work in all cases. In other words: VB.NET lacks re-implementation of interface members and with classes like DataTable in .NET (some winforms controls also have some interface members implemented privately, so you can't re-implement them) which have a privately implemented ISerializable, VB.NET can be a struggle in some situations, so be careful which language to pick for some of your classes.