Quick and easy installation.
Very easy and user-friendly GUI.
No stability problems. I like the variety of settings (plenty of models, adjustable proximity effect, possibility to choose the polar pattern of each model, and the filters provided with the different models) and the tube simulation which can actually enhance an average guitar recording.
The sound is good but you don't always have to select the mic model you would have chosen in real life to get the sound you want... You'd better try out several models.
The only disadvantage is that the plug-in needs a lot of resources (I use a 2.8 GHz CPU with only 512 MB Ram) and I can't use more than two instances in the same project. I believe a DSP version would be a great idea (If it doesn't exist yet...)
I used it regularly at a friend's and it surprised me. Obviously you can't expect a Neumann sound if you recorded with an SM58, it's only a computer-based simulation.
But this plug-in is very convenient to record vocals and guitars with a vintage sound.