2. Rush Hour - we travelled several times in what would be considered "Rush Hour" in most cities (ie between 5-6.30pm), and not once were we crammed sardine like into a carriage with our faces smooshed against the glass, which is a common occurrence in London, neither were we subjected to a smelly armpit in our face.. in fact the rush hour period was barely distinguishable from the rest of the day. My only conclusion can be that A. Parisians don't finish work the same time as the every other major city in the world, or B. because they keep the trains running regular the entire day - thus keeping everyone moving at all times, rather than trying to put on a few extra trains at peak times.. I swear we never waited more than 6 minutes for a train.
3. Air Con - now I don't know for sure if the Metro has air con, but despite it being 30c outside, the stations and trains themselves were fine, not humid or sweaty, maybe it's just that their tunnels are bigger? Either way, being able to travel by underground train in august at a temperature that do not exceed the legal level for transporting livestock is a plus point.
4. Vending Machines - Unless there has been some radical changes in the 6 months since I last stayed in London, the majority of platform vending machines were full of chocolate bars. Not very useful say when you're about to faint through dehydration (see No.3). Needless to say every platform we used on the Metro (and there were plenty) had vending machines that stocked most importantly - Water, and lots of it. Along side various sodas, crisps, and haribo - Bonus!
5. Buskers - I have to say I have no qualms with people busking, on the underground or anywhere else, but in Paris we saw a puppet show (although I have to admit, we were subjected to some pretty awful dancing and karaoke).
6. Doors - the doors on a lot of Paris Metro trains are not controlled by the driver! which means (as we often saw) that you can open the doors a second or two before the train fully stops to jump out! It also means the doors only open if people are entering/leaving the train.