Some issues we have noticed with the designer:

1. Can not determine design mode before the properties are actually set,
making it difficult to code the connection of controls? Is there a way to
tell design mode earlier?
2. Controls/Components that need to know when all properties have been set
need to use ISupportInitialize BeginInit, EndInit and use the EndInit call
BUT Begin and EndInit are never called when the component is first dropped on
to the form, making this an unreliable method to use for design mode.
3. When putting user controls in panels sometimes the designer just loses
them? Any work around, many people have reported this issue.  The only thing
we could do was move code out of initialize component so the designer would
stop dropping the control.
4. It seems depending on when you use GetReferenceService can change the
results of what you get... sometimes it only will retrieve controls and other
times components.  Is there some sequence diagram someone has to show when
particular methods are called on the component in design mode and at what
points things are useable?