Your sarcasm is noted. You may have noticed that Peter and I have a few blue bars lit up under our names - that's because we've answered a lot of questions and helped a lot of people over the years but you happen to have asked a question that is very hard to answer. On the one hand I can say, "You own a Mac. Downloading and installing software on a Mac is simple. On the Mac, installing software is almost never dangerous - I can probably list the number of truly awful and dangerous Mac programs on one hand with at least the thumb left over. In truth, if you download a program that is listed on Macupdate or VersionTracker it is almost certainly safe and if you aren't sure, read some of reviews about the program. Indeed, as Peter said, both download sites are a good place to go if you want to know what users think."
Now, having gotten that out of the way, the real question is, "Is the Avery label program a worthwhile download?" That is the question Peter and I really cannot answer for you. I don't think it is particularly good. It works only with Avery labels, it has some annoying shortcomings, and I'd rather grab a template for the labels I've bought and design my own labels using Indesign and Photoshop. My wife has no graphic arts background and while she uses Photoshop to do some basic photo editing, she isn't very knowledgeable about it or Indesign. But does that information really do you any good? And given that you can download the program and try it for yourself (the joys of *try before you buy!* ) why ask? Just give it a try and see if you like it.