I use the Slim Clip Wallet when traveling and want to minimize the possibility of someone picking my pocket in an airport or train station.  I think it works well when traveling.  When closer to home I don't normally use it due to needing to carry more stuff in my wallet than the Slim Clip will hold, but when traveling I don't need all the extra items and it works great.  If you are like me and have a fat wallet due to all the cards, licenses, insurance cards, etc. and wanted to use the slim clip all the time; I might suggest you get two.  You could put your cash and credit cards in one and all the other "stuff" in the other.  Then put one in each front pocket.  I like the way the credit card slot holds the cards stacked perfectly in the clip.

Overall I think this is a great product and can't really think of any way to improve on it.