I was under the impression that this was the all-time favorite tourist spot in Vienna. Many traditional (or, say, less hip) Japanese guide books indicate that this is one of the must places to see.

I never knew that the clef flower bed came in colors other than red. They always show the red one.

And the garden was empty when I went, sort of mid morning on a Friday.

I like the G clef!

It seems that in other countries, he seems to be more the attraction rather than the clef or in Japan it's the combination thereof if anyone finds this particular spot to be interesting for tourists to visit.
http://www.wienvienna.com/mozart-statue-vienna-burggarten-hofburg/
If you read both English and Japanese, the contrasting reviews below are funny. The fact that there are more Japanese reviews is interesting, Tripadvisor not being particularly popular in Japan.
http://www.tripadvisor.co.uk/ShowUserReviews-g190454-d319282-r82785909-Burggarten-Vienna.html