The broker is the least exciting component to talk about. In the View world this is the single point of management for everything, in the Citrix world its one of many but its very important. The broker is what the client talks to in order to know what VM it is allowed to access. If you are familiar with XenApp then the broker isn't really going to be something that is scary, it looks a lot like the management console you are used to seeing. If you have never touched Citrix before, then you'll have something new to play with. Honestly, the Citrix broker looks like an MMC so anyone should be able to jump in and learn it pretty quick.
The View broker, aka View Connection Server, is managed via a Flash based website. I really like this approach as its OS agnostic and doesn't require you to install anything to manage your View setup.
In all honest, in both cases the broker isn't really that exciting. The broker is the man in the middle. He sits there and waits for connections, when someone logs in, the broker is the one that checks with Active Directory to make sure the user is authorized. Then it checks its own DB to figure out what desktop this user has access to, finally it gives the user the list of desktops and eventually hands that off.
A broker can be load balanced easily with both View and XenDesktop. The only major difference I see in these two is that one is webbased which is easy for a new person to pickup, and one is "Citrix" based, so its easy for a Citrix Admin (which I am) to pick up.