Is that open wifi really letting you access the web? Network Tester quickly validates you're connected to the real web (by downloading a very small dedicated file and checking its content). If the hotspot is actually redirecting you to a billing portal, you'll know instantly.
For troubleshooting any data connection, you can also validate hostname resolution and TCP connection.
And for statistics and fun sake, Network Tester lets you measure downlink speed on a 10K, 100K and 1M HTTP download.
Network tester is open-source.