This hotel, located right by the Luxembourg metro stop, is great. The rooms and bathrooms were very clean and the maid service was excellent. We stayed in a room with a shower, and we had fresh towels everyday, as well as a cleaned room and bathroom; the WC was in the hall, and, while it was sort of old, it was also very clean.

You don't go to Paris on pleasure and hang out at your hotel a lot, but when we were there, it was very cozy. The radiator didn't work very well, but it was never uncomfortably cold, and I'm sure they would have moved us if we had asked. Breakfast is simple, but the staff that runs it is very friendly. The views from the windows are very nice, and it's close to everything. Plus, you are literally almost in the middle of Paris for 65 euro a night, which is crazy. I would definitely recommend this hotel.

One unexpected caveat is that wifi is not free, but the prices for it were very reasonable, especially considering breakfast is now included.

This is quite an old hotel but is in reasonably good condition. When we checked in the bathroom wasn't clean to my standards, but then the daily maid service seemed to remedy that. The staff speak very little English so do brush up on your basic French.
Our room had a quaint, cozy feel to it and was quite roomy. It was very cold when we were there, and the maid liked leaving the windows open when she cleaned the room, so we would come back late at night to a frigid room. There wasn't any heat turned on the entire stay even tho it was bordering on winter there.
Either that, or the heating system just wasn't efficient. Street view was wonderful; if you are a light sleeper, the daily street cleaning equipment in the early AM might disturb you - but that is Paris.
The bed didn't have pillows just one long hard big bolster that was the entire width of the bed - to share. Ended up using our coats for our pillows. The hallways were a little dark.
The location, in the Latin Quarter, is great, very close to the metro.
Rates are very good for expensive Paris. I thought breakfast was good (croissants, breads, jams, coffee, pot of tea, hot chocolate).

I stayed here for one night for 60 euros (no WC) for a double room and it's not the best, but also cheap. I can't easily think of anywhere cheaper in expensive Paris. Even hostel dorms are only a little cheaper. Our bed was shaped like a (bracket) tipped on its side, so we both ended up in the crevice in the middle. No bed bugs or anything however, that's thje main thing. "Cheap and not-quite-nasty", is a good way to describe it. Didn't eat breakfast so can't comment on that - just go out and buy a few croissants for 1 euro each as you walk past any bakery - cheaper and more Parisian that way. We left our luggage in the room and retreived it no problems that evening - but no one checked what we took, it could've been anything, so i empathise with the person who had stuff stolen. After one night we found a deal - 80 euros a nite one of the many hotels further up the street, which is much better value even for a cheapskate like me. To summarise, staying at Hotel Gay Lussac is certainly bearable, if you want somewhere cheap or if there's nowhere else to stay that isn't double the price. The Latin qtr is the absolute best location to stay in Paris, no doubt (for restaurants, pubs, walking). But try to find a deal with another hotel in the latin qtr for 80 or 90 (there's a bunch next to each other just further north). If not, put up with this for 60 a nite, and, like the beds, don't be so soft!

Stayed four times already. It is an affordable hotel in a good location in Latin Quarter, very close to Luxembourg RER station.
I always walk to Notre Dame from there having a stop for breakfast at Place de la Sorbonne. Walking takes about 15 minutes through Boulevard St Michele.
Rooms are very basic, somewhat tired, but clean. Expect nothing special. Try getting a room on higher floors with a balcony, get a bottle of wine in neighborhood shop and you'd be ready to comprimise as prices are very good for outrageous Paris.
Never tried breakfast there.
Staff is very friendly with really nice grandma and grandpa during the day and a fun young lad during night hours.