official website of 3ddesktop doesn't mention if it is a beta. Not every software that has version number less than 1.0 is a beta, and not every beta software has a version number less than 1.0. Beta versions are those that are still incomplete, in testing phase, and final tweaks are required before they can be passed on to the community. For example, Windows Vista was in Beta for quite some time, but GNU/Linux is not in Beta technically.
In a nutshell, 3ddesktop is safe in my opinion, but if you have more doubts, feel free to contact the author of 3ddesktop.