Was there a few weeks ago.
BEWARE: ATC is all in French. Only French. And RT French, at rapid fire, is very different to being competent on the ground. Both I and the person I was flying with speak very reasonable French, and we had serious issues comprehending what ATC were telling us. If you could only understand the circuit calls you might just be able to get by, but it would be a challenge.
The aerodrome is right up against the Paris zone -- there's a good visual approach chart on the SIA website (St Cyr is ICAO LFPZ if you didn't know that already). Turning finals for 29 means not going beyond the western extremity of the Palace de Versailles lakes (so no bomber circuits, or you'll be in trouble. Refreshing, if you ask me). Two parallel runways, both pretty sizeable -- SOP for the northern one is to vacate into the middle and then wait for clearance to cross. All the grass is in very good condition. The tower may ask you to park on the grass apron to the west of the tower -- if you can persuade them to let you park by the Aeroclubs you'll have a much shorter walk into town.
There is a c.1 mile walk into the town of St Cyr to find a bus or rail station, but when you do there's a good selection of buses into Versailles and regular RER into Paris Montparnasse.