Stayed as a family with 2 kids in late September 2012. To be very honest we chose this place because there was hardly anything else decent available in the whole central Paris. We wanted a room or a suite where we could all fit but sleep in different rooms. Luckily they had such room for us so we were happy to finally find a place to stay, however, the price was quite high.

Location
Near Louvre on Rue de Rivoli it is located fairly conveniently. Everything is about 7 min walk including nearest metro/RER station, Louvre, Cite (maybe slightly longer but still very manageable). Rue Saint Honore is next turn and is offering nice choice of café, restaurants, and shops, becomes main boutiques street after 10 min walk. It is an old district so you can expect nice architecture and a very nice ambience around.

Room
It is half-way to design hotel. At least some of the amenities are definitely there for beauty not for use. Light switches are not where you want them and they puzzled us initially by their operation. Sanitary equipment was not in good order. Toilet could not be used too frequently as it would not accumulate enough water in reasonable time. Bathroom tap was not broken but slightly worn out with some parts missing.
Otherwise the room was clean. Room cleaning service brought no issues. Wi-Fi was free, however, it was dropping signal all the time.
Our room windows were facing the street and as we are used to open them at night we had to survive through terrible noise made by construction site nearby, which apparently never stopped activity even at night. No one really made any note about this to us when we were booking or checking in but we are used to this kind of things in other places as well.

Other
Breakfast facility is not big enough. It is actually very small. If there are more then 10-15 people having breakfast at once you will not be having yours. We faced it at least once. We had to wait for at least 15-20 minutes and when we expressed our dissatisfaction with this issue we were grilled by the attendant at the facility that it was actually our own fault that we wanted a table for four and they never offered us any alternative. Otherwise the breakfast content was quite good with a very good choice of top class bread, croissants, meat, etc.
Reception was mostly helpful. We can only note that their choice of nearby restaurants was quite limited. It could be that there are just not many good family restaurants nearby though.
There is only one small lift so traffic jams are not unusual in the peak hour. It is essential as the hotel is very narrow but has many floors.

Overall
If not location it would be a pretty average experience. We think it deserves its place in Tripadvisor ranks. Not more not less. It is maybe OK for Paris but in European context it is not value for money.

Ideally situated in the centre of Paris close to the Louvre this hotel was a pleasant find in the city. It is a boutique hotel in a modern style. The staff are friendly and efficient and rooms well appointed. The breakfast was wonderful with a good selection. My room was quiet and it the hotel is just a little bit removed from the busier main streets in the area. There is some renovation/construction work going on in the building next door but there was no noise from that area except during the day. Definitely better than the large chain hotels in Paris or the rather run down three stars with grumpy staff and plastic breakfasts that are so common in Paris.

We've stayed in Paris a number of times and would have to say that this hotel's location is excellent for exploring all areas of the city. It's within walking distance of the Louvre and easy walking access into other areas of Paris.

Check in was fast and the front desk staff very friendly, in fact all staff here were helpful and attentive. Breakfast was included in our room rate and was excellent and service prompt and friendly. Our room was on one of the lower floors, the hallway was a little dark and the carpet needs some attention, it was a little scruffy, which did detract from the overall experience. The room was quite large and we had no problems with the cleanliness nor housekeeping service whilst here. Internet access was easy to set up and the speed was fast enough for me to upload fairly large files, so this is a good choice if you like to use fast Internet service.

There are a number of restaurants surrounding the hotel, which provide very good quality meals so you don't need to walk to far.

Very nice hotel that we sincerely recommend for location, service and friendly staff.

These are the strong points of L'Empire: The staff! The rooms! The service!
This is the soft point (which is out of anybody's control, but still nice to have): The Location!
All of the above were perfect and made our stay in Paris (6 days, 5 nights) in late October a treat.
The staff is very, very helpful, to the point that they will try to solve your problems, even before they even occurred.
Our room (junior suite) was just redone, had a large twin bed, a television in each room, a big bathroom with shower and bathtub, more than enough space for two people. It could have slept four, as there was also a foldout couch.
Location in Paris is essential. The L'Empire is situated close to the Louvre, the Notre Dame and it is in the trendy Marais area of Paris. Restaurants, shops, galleries, it's all there. The wife loved it, so did my credit card company. I did, too. The statement hasn't come yet...
Having said all this, please remember, you are smack in the middle of a huge city! There is traffic, there is construction, there are garbage pickups. So no, it is not quiet, but you will not have that in any city. If you want quiet, visit the Paris cemeteries.
We will have to come back, as there are some things we didn't see, and we will surely book in the L'Empire again.