The price is the same as for 1Gbps and 10Gbps (~60USD/month) - though the initial setup price differs: ~300USD for 25Gb/s vs <100USD for 1Gbps
The actual speed within network is indeed 25Gb/s to some fellow users running speedtest.net servers. Inside Switzerland it's maybe ~15Gb/s to some well connected servers in the area of Zurich, and ~10Gb/s across EU. Tested with speedtest.net and iperf.