5G Stand-Alone (SA) deployment is crucial for unlocking the full potential of 5G, providing significant improvements to mobile user experience and enabling the development of new applications. As mobile operators start rolling out SA-5G to the market, there remains a lack of comprehensive measurement studies, leaving many questions about its capabilities. To this end, we conducted a timely in-field measurement study in April 2023, covering two major US cities where T-Mobile has designated SA-5G as the dominant and default radio access technology. Our study gathered over 10 hours of insightful network traces under different mobility scenarios. Using these datasets, this paper examines the characteristics of the recent 5G SA deployment, data plane performance, and mobility management. Our study provides a revealing snapshot of the current state of SA-5G in the US. We show that SA-5G exhibits improved performance over NSA-5G in many areas. Whereas we also identify areas where SA-5G yields poorer performance over NSA-5G.