I was not sure about switching to this type of wallet from a normal wallet because I thought it might be difficult to get my cards out.  To my surprise, my id is very easy to remove and my credit cards take about the same time to remove as they did with a normal wallet.  I used to take my wallet out of my back pocket when driving cause sometimes sitting on it would cause pain.  I can barely tell this wallet is there.
The only downside I see to this wallet, is that it is difficult to get to your cash when compared to a full-sized wallet.  It just doesn't matter much to me because I only use cash to give my kids their allowance and some very random things here and there.
Plus, with this wallet, the cash is hidden really well.  My primary use of cash used to be my wife taking it out when she needed some money.  I don't think she realizes that there is any money in this wallet.