I use start all the time, but also frequently curse at its stupid argument grammar and its interaction with auto-quoting on auto-completion. For example, type
start C:\Doc
Next, hit tab to get
start "C:\Documents and Settings"
Now, hit return, and watch a new command window open with title "C:\Documents and Settings".
Reason? If the first argument is a quoted string, it is used as the title of the window being opened (http://www.microsoft.com/resources/documentation/windows/xp/..., http://stackoverflow.com/questions/154075/using-the-dos-star...)
If you ever use start in batch scripts, pass a dummy first argument of ""
Next, hit tab to get Now, hit return, and watch a new command window open with title "C:\Documents and Settings".