Attribute binding is how MVVM should be implemented but currently the following limitations have forced me back to widget-binding ...

1. Some data attributes are not supported (eg. grid "autoBind")
2. Attributes cannot refer to external templates and these must be defined inline.
3. Line breaks are not supported making long inline definitions hard to read and code.

I suggest attribute binding (and documentation) is developed in parallel with widget binding.

I believe TabStrip is not supported with SplitView as SplitView can not be used in a view. This is inconsistent if the application needs a common TabStrip across all pages.

Should be able to enable and disable switch.

Sorting accented characters currently is not supported out-of-the-box and we must use ServerSorting to be able to custom sort the items and send them to the Grid. 

The grid should sort accented characters directly on the client. 

Grid._toolbar function:
toolbar = isFunction(toolbar) ? toolbar({}) : (typeof toolbar === STRING ? toolbar : that._toolbarTmpl(toolbar).replace(templateHashRegExp, "\\#"));
if toolbar a function, you don't escape # characters, which results in invalid template function generation

I have a master detail grid and simply would like to place captions on them.

The js executes successfully, but the captions don't appear when the View is fully rendered.

I'm using the MVC wrappers, I have a foreign key column in my grid and I use the standard foreignkey editor-template. It is not possible to bind a null value (foreign key not set) to the dropdown. It works when I change the template and replace the kendo dropdown with the standard mvc dropdown.
So I guess there's a problem with null values on the kendo dropdown

There is a bug when cancelling the edit of a row that was loaded through virtual scrolling from a remote datasource, the row disappears from the grid/datasource. Telerik confirmed they can reproduce the bug but due to the specificity of the virtualization process currently do not plan to provide a solution for this. Their recommendation is that if you need editing with a remote datasource to disable virtual scrolling and enable paging instead. Vote for this to have the bug fixed.

add the ability to choose the weekly in datepicker

In a kendoTreeView if I define the dataSource as an observableHierarchy, then expand(".k-item") expands only the first level but if I execute it twice!!! it works correctly

If I use text method for changing the text of a node in a treeview, the icon gets removed. Same happens if the dataSource is an observableHierarchy object and I use set("text", newText).

Won't hurt to have one, to have a KendoUI version would be pretty in the eyes. 

and a grids toolbar with the commands and template at the same time throw a search input text that filters the grid. 

To speed up website load time dramatically, it should be possible to cache and load static KendoUI-Files from the local browser storage.

Discussion / Example:  http://news.ycombinator.com/item?id=4733102

Maybe KendoUI can also provide us with an API to store files, data etc. on local storage...

Sometimes need to disable column selectable option. For example, when column consists checkboxes or action buttons.

$("#users-grid").kendoGrid({
  dataSource: {
    data: createRandomData(20),
    pageSize: 5
  }
  selectable: 'row',
  columns: [
    {
      field: 'UserId',
      title: 'ID',
      template: '<input type="checkbox">',
      selectable: false
    }
    {
        field: "FirstName",
        title: "First Name"
    },
    {
        field: "LastName",
        title: "Last Name"
    },
    {
        field: "Actions",
        title: "Actions",
        template: '<a href="">Delete</a>',
        selectable: false
    }
  ]
});

Would be nice to have a way to easily configure columns to be fixed (position and width), like a checkbox column to select rows.

This kind of column need to have fixed width and position (cannot be reordable).

But, KendoUI could has also a native support for rows selection, allowing us to just turn on this feature that could have a lot of sub-features: Remember selected rows by page, mark/unmark all, custom options in the column menu to massive mark, and so on.

KendoUI would seriously benefit from some killer apps and more marketing in general. A showcase gallery would be a great place to start.