While everyone is excited about this official client, I'd like to give a HUGE SHOUTOUT TO BOOMPJE AND HIS TEAM. When Riot shut down the first Mac client project, Boompje took it upon his own shoulders to personally script his own launcher (which, IMO, is actually better than Riot's, in iLoL 2.0, check it out!), and do everything for us. Appreciation to Boompje and his team!
Also, @Riot, the new launcher for the native LoL client for Mac seems awfully small. It only seems to take up about 1/4 of my screen. This may be due to me using a 15 inch Retina display MacBook pro, but hopefully there will be an option for resolutions.