I can answer this one form someone that is rather new to knapping and also as a person that started with glass and obsidian before going to flint. It isn’t that you develop bad habits; it’s more along the lines of it being a lot easier. I started with glass because that was cheap and easy to get. I eventually bought some flint and almost gave up knapping because it was so difficult. So I bought some obsidian and was happy again. It was just like working glass. The truth is that it gave me a false since of accomplishment. By that I mean it make me feel like I was really knapping, but every time I picked up a piece of flint, I destroyed it. And before everyone starts throwing obsidian flakes at me, I am not saying there is anything wrong with working obsidian. It is a great median and I learned a lot of basics from glass and obsidian. And when put on the end of an arrow, obsidian will bring down game just as well as flint. But the bottom line is that, in my opinion, working obsidian is a lot easier than working with flint and it is a lot more forgiving. And in my case, it made the transition from obsidian to flint a whole lot harder. This is provided the person learning to nap wants to learn to make tools of flint. If they don’t, then it is all immaterial. Not that it has anything to do with topic, but I will say one other thing about obsidian. Be prepared to bleed, it just comes with the territory. I dripped color a whole lot more when I was working with obsidian.