eduroam is based on the most secure encryption and authentication standards in existence today. Its security by far exceeds typical commercial hotspots.
eduroam requires the use of 802.1x which provides end-to-end encryption to ensure that your private user credentials are only available to your home institution (your college/university). The certificate of your home institution is the only point you need to trust regardless of who operates any intermediate infrastructure.
Be aware though that when using the general Internet at an eduroam hotspot, the local site security measures at that hotspot will apply to you as well. For example, the firewall settings at the visited place may be different from those you are used to at home, and as a guest, you may have access to fewer services on the Internet than you have at home.