I could not find anything wrong with it, very accurate and reliable. It just wasn't a Walther, so I sold it and bought another P99. It confounds me why the military is not using the G17 and G19instead of the more expensive Berettas and Sigs.
To answer your question, the only thing I don't like are the plastic sights, be we have all heard that a million times.
I liked my G19 ok, but didn't love it. After i bought the P99, i found myself never shooting it and not missing it... so i sold it. It's a very good gun, and in my opinion the BEST gun that Glock makes; perfect size, ok ergos. But i prefer the Walther; i'm far more accurate with it.