There are others binding around, being Monobjc the most advanced one and more feature-rich from my point of view. The MonoMac approach is more dotNet-user friendly as it has .Net naming convention. This introduces a few requirements that I feel like a drawback more than an improvement. This naming convention needs a new and consistent documentation that allows the user to under the framework which will make the life harder if you are also reusing objective-c code, you cannot translate the code easily since you need a conversion step and You cannot either easily use the vast amount of cocoa documentation and examples found in the net, as the Cocoa api and MonoMac api are not named equally.
The other problem so far is the lack of examples and documentation in MonoMac, something that Monobjc project has solved from the early stages.
A new binding won’t do any good to the community, the user swill be spread around this two projects, lowering the final quality of both. We will continue with monobjc and we are looking forward to the new upcoming changes.