My husband lived in this hotel for 6 months until June 2011, for work purposes. I stayed with him for about half the time, because I couldn't stand it for too long! Algeria is probably one of the most boring places I have ever been to....but that's a separate issue.
Focusing on the hotel, it's a typical large 'chain' hotel catering mainly for business clients. It's fair to say it's not the most modern design, but it seemed reasonably well maintained. It's a popular venue for weddings in Algeria as well, so there are often bridal parties passing through reception (quite a spectacle).
The room that we had was quite spacious, with a comfortable King Size bed. There was also a coffee table and two chairs, plus a desk area. The bathroom was small but functional, but looked a bit dated. Our room overlooked the pool/gardens. This was nice, apart from on a couple of ocassions when large parties were held on the roof terrace in front, complete with loud music and dancing well into the early hours. The hotel management didn't seem to appreciated that most guests were on business and had to get up for work the next day, unlike the party go-ers. My husband went down several times to complain, and even though he can speak French and Arabic (which really helps in Algeria) he was simply ignored or told "5 more minutes"...which of course never materialised.
The best thing about this hotel is it's proximity to the new mall, which is only a 5 minute walk away. Whilst only very small, the mall is the highlight of things to do in Algiers (!). At least there are cafes and restaurants in there to make a change from the hotel food, which is predictably expensive and the menus never change! The mall also contains a supermarket. As an obviously "foreign" woman walking alone, I felt quite happy walking to the mall during the daytime. I did not go further afield though, as there was nothing to go and do anyway!
The Ibis hotel is next door to the Mercure, so we often chose to go and eat in there in the evening. The dining is less formal and the food was very good quality. My husband had been told by colleagues that the rooms in the Ibis were very small - that's why he chose the Mercure. The Mercure also has very nice gardens, tennis courts and a large swimming pool (not heated). Most of the staff I met were very polite and smiley, even the maids and gardeners who didn't speak English. Ironically, the least friendly were the women on the front reception desk!
Unfortunately, there are only 3 major hotel chains in Algiers (Sheraton, Accor & Mercure) so demand is high, as are prices. You would not be happy to pay these rates anywhere else for this hotel, but in Algiers beggars can't be choosers!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC