I am quite new to the beta - second day - an up to now I only have a single problem: the VA toolbar gets visible on startup of VS.NET 2002 and 2003 even if I closed VS.NET without the toolbar visible. If I close the toolbar before I open any solution and then do open a solution the VA toolbar pops up, too. After that point I can close the toolbar and it keeps closed - until I restart VS.NET when it pops up again...
Over a year ago I bugfixed a collegues addin for VB6 where he used the wrong callback method to set the position and visibility of his toolbar. So maybe there are some dependencies in the VS.NET addin models interfaces also? As e.g. SourceSafe is able to get the toolbar visibility working I would guess that it is a bug. Even MS has sometimes problems with their own IDE programming model: I am alpha testing Whidbey - the next VS - and they have one docking window "DataSource Fields" in the PDC version which keeps getting visible no matter how often you say good bye to it :)
But don't get me wrong: all the other parts of the integration in VS are truely amazing. Syntax coloring in the class view and in the member combobox. Only the object browser is not fully syntax colored.