FLZ Vortex also looks interesting. By default the interface is in German but there is an option under the "Sprache/Language" menu to switch to English.
The documentation with all of these programs say that they're not for full scale use. My personal opinion is that this is just the standard legal disclaimer that comes with all software. It's obviously not as high quality as some other programs but unless you have the budget of Boeing you should never consider software output an actual design until you've done some other form of verification (like build a test piece and actually test it). Comparisons with tunnel results shows the airfoil data from software is ususly good within the linear range but may be optimistic at the extremes ie CLmax is sometimes too high and CDmin is sometimes too low (these errors can be as high as 10%). Also PC generated post stall can be a complete crap shoot.
One thing I like to point out is that this software is relatively new whereas the code that Harry Riblett used to create his airfoil sections was written in the early 80s and if it didn't have the same disclaimer it should have. So, is it irresponsible to use free or cheep software? Only if you go directly from the screen to the plane with someone's butt in it.