It's pretty bad in Paris - many museums are closed due to having to move artwork out of underground storage, some underground attractions are inaccessible, some Metro stations closed due to water, no cruises on the Seine...
Lots of disappointed tourists with nothing to do but wander around taking photos of the muddy water from the bridges. The river did crest late last night, but the water is expected to remain at its present level for about a week - and maybe longer, if it starts to rain again. Hopefully, things will getting back to normal after that. The main concern are underground electrical cables which have been inundated and will have to be repaired, and the ventilation systems of the affected Metro and train stations which must be completely dried out before anyone can use them.
In addition, there is a transportation strike involving inter-city trains, RER C, and some portions of RER A.
Despite the strike, train service is running, but on a greatly reduced schedule. Expect major delays, and though your ticket may be used on the next train with no penalty, you won't be assured of a seat.
It's not a good time to plan a trip outside Paris - either by car or train - since many highways in any direction are still under water, and the chateaux in the Loire valley and Fontainebleau are inaccessible due to flooding. Getting to Versailles will be difficult, without RER C.