I traveled to Montpellier France three weeks ago and bought a prepaid SIM from SFR (France's #2 mobile carrier) for my unlocked iPhone. Montpellier is France's fastest growing city and its 8th largest. Here are the speed test results from CalSPEED from a test I ran near the Place de la Comedie, pictured below.
As we saw with 3G/HSDPA technology in California, ping times were long, between 342 and 347 milliseconds, and hampered real-time streaming capabilities. Granted, my phone was pinging servers on the east and west coasts of the United States, but if I were using LTE instead of 3G, I would expect the ping times to be in the range of 150-200 milliseconds for CalSPEED.
This was my first time using a prepaid SIM from a local carrier, and, not knowing how much data to buy in advance, I bought 20 gigabytes. I thought that would be fine for two and a half weeks of exploring the Languedoc area. To my surprise, by the end of my stay I had only used just over 1 gigabyte, and that was with heavy daily usage. Rather than data, it was battery life that ended up being the limiting factor.
Montpellier has a large student population and there are many new cafes catering to them. Pictured below is a sandwich board written in English, tongue-in-cheek.