Firstly I'd like to say congratulations to the cycling 74 team for their work on Max 6. Especially for the dict object, that's going to be incalculably useful for my future projects.
Generally I think that a lot of the patching UI changes are positive developments. Curved patch cords are a blessing. The new autocompletion is very smart and I can definitely see a massive increase in usability for people new to the software. However, I think there are some major inefficiencies in the new window model, the new object explorer and the sidebar.
To me, the object explorer feels like a step backwards. The old object palette was perfectly suited to the task of creating new objects. You could easily see where the object was going to be placed, and you had one click access to any available object. It also allowed really easy access to prototypes, which now requires the object to be created first.
In the new object explorer, I can't see everything at once, I have to scroll up and down to find the right object. I also now have to click and drag all objects onto the screen to get them in the place I want. This is really inefficient compared to the old method. The fairly obvious alternative to this is just to use the new object shortcuts, but this seems to go against the idea of making the software easier to use. Also, as a terribly inaccurate typist, it's quicker for me to perform two clicks to select an object from a palette than it is for me to press N and try to type the object name.
In Max 6, all double-clicking does is bring up the object explorer window (or pulls focus to it in the sidebar), which then does not disappear (or switch focus back) when the object creation process has ended. The interface effectively forces you to constantly have an area of your screen taken up with a fairly large display of icons. This is wasted space. I only need to see this window when I'm creating a new object.
Another unrelated annoyance for me is that the colours which served to differentiate attribute categories in the inspector window have gone. I can't really see why these have been removed. They definitely helped me easily identify attributes and navigate the list.
I can absolutely appreciate the need for the object explorer to exist. It's a good way of quickly browsing objects (and the fact that all typed objects are now included is a big plus). But I can see that it's going to slow down my workflow a lot. I'm not saying this out of lack of willingness to change my patching habits, but I really think that this new system is a step backwards. Please bring back an option to use the object palette.