I know I will be burned at the stake for admitting this, but I have been using your run of the mill Uncle Mikes IWB with my LC9 so far. I have used them off and on with new guns when I am not ready to invest in a $50+ holster, I don't want to wait for the ordered holstered to show up or I am not sure what holster I want to order for full time use. The good thing about the Uncle Mikes IWB holsters and also the Blackhawk variant (which to me is the exact same thing with a different name) is that they are cheap and readily available pretty much everywhere. The bad thing about them is that they don't always work that well. In fact I would say more often than not they don't work that well.
To me the biggest mark against the Uncle Mikes style IWB is the plastic clip. They usually are not very good at holding the holster in place on the belt. If you do anything that requires repeated bending, sitting etc. (no matter how infrequent) you will generally have issues with the holster not staying in place. Even with a "gun belt", like a 5.11 Instructor belt you will still have issues. You can pretty much forget about any type of running or fast movement. The nail in the coffin is the holster not staying in the waistband when the pistol is drawn quickly. It may not come out every time, but often enough to be a big deal, especially if you are using a shorter barreled gun (at least this has proven true for me)