I use the free version of WPTouch on several of my websites and have had good feedback and compliments on it. I use all the standard "factory" settings - since I'm really not too sure what the options are all about.
So far the only report of a problem I've received is a user said the "Search" function was grayed out and asked if that would be fixed. The search function is pretty important for this particular site's users. I don't think this is a problem with the free version but I'm not sure how to find out what's going on.
In any case, I highly recommend it.