On a United Airlines flight today, I decided to try the in-flight Wi-Fi just to see if it was a viable service.
In Google Chrome or Safari, attempting to use the in-flight WiFi shows the payment page to initiate access. In OS X Safari (OS X Mavericks 10.9.3), Safari just hangs with a blank page. Retrying and reboots to no avail.
So I tried Chrome. After figuring out that the sign-in payment form had truncated my confirmation code because I had pasted in a space (rather confusing error), I ran into another roadblock. Presumably it all works, usually, but I checked with my seat neighbor and it had gone dead for quite a long time.