I'm not convincing anyone to use WME, there are many engines out there to choose from and all of them are great (and all of them have their pros and cons...). Some people like WME the best, because it offers them a good ballance between ease of game development and flexibility for non-standard operations. Some people like the speed, provided by the 3D acceleration, etc.
But the final choice is yours. If you are serious about an engine choice, you should download them all and test them for a while, because *you* are the one who's gonna use the engine, it must suit *your* needs, and people's needs are very individual.
And to your last question, no, I don't think WME is a good choice for a total non-programmer. Although you are provided with prefabricated scripts and basic operations can be achieved by a few simple commands, you'll probably realize you need to do some complex actions in your game and those will definitely require you to do a good deal of scripting (unless you are going to make a very simple game...).
Well, it would be nice if people who are actually using WME write here their opinions. What they like, what they don't like, what is their experience compared to other development systems... You can hardly expect me to be truly objective on this matter