Still wish they would implement something better for INotifyPropertyChanged like key-value observing in obj-c or object.observe proposed for js. Basically automatic property changed events. At least this removes the magic strings in the boiler plate.
I've really wanted to have some sort of property token similar to how we can use method groups as tokens for event subscriptions and delegate creation.
I've also wanted a system similar to dependency properties in WPF that was a little lighter weight. DPs do pretty much everything i could ask for from change notification to binding to pluggable validation, I just wish they we not so tied into the WPF code so i could apply them to my data layer.
I really really want property change notifications on auto-properties. Having to compare the incoming value against an explicit backing field is the cause of most of my boilerplate code when using WPF.
But my feeling is that it was kind of hopeless to do in C#: it is just so different from the language semantics. Something like FRP (real FRP, not Rx) or managed time [1] works much better, IMHO, but requires drastic language changes.
JavaFX Script (F3) also included data binding straight into the language, and is probably an idea of how to do it for C#.
