Last week I bought a Holga on eBay (with flash), and this weekend I shot my first roll of medium format film. What a treat.
Shooting with the Holga is a liberating experience. Yes, there's barely any controls on it, but that's part of what makes it great. You just have to know how to leverage its limitations.
The fact that people still use this camera, and are creating amazing work with it, is the perfect fuck-you to today's conveniences and technologies, both in and outside of the camera world. This camera forces you to embrace its limitations, find ways to work with and around them, and in the process it turns you into a better photographer.
Example: It only has one shutter speed. That means you may need to choose a different ISO speed film to shoot with for a particular shot, or you may have to shoot at a different time of the day, or you may have to shoot on bulb mode, and calculate a longer exposure time yourself. Or, you know, shoot something else.
When you're shooting with a modern digital camera that does most of the work for you, you're learning considerably less.
That's not always a bad thing. Photography is about more than technique and settings. But my position is that when you're forced to make more decisions about making the image, it gives you greater ownership over the finished work.