The only problem I've had is that my trigger finger tends to drag a bit on the trigger guard. Personal ergonomics - your mileage may vary. In extended shooting sessions - not the intended use for the pistol - my finger can get a little tender there. Big deal.
It's not my first choice, as I prefer my Government Model .45, but it is a good choice for certain situations.
Bottom line: At this point I like my CM9 and I trust it.