My wife and I ate twice at Le Cosmopolite on a Friday and a Sunday. On Friday, the restaurant was extremely busy but in a good way, as it had a really lively atmosphere. This was due to a combinatin of the crowd, the very good 2-piece band playing traditional folk and international songs, and the pleasant interior, which features lots of timber and plasterwork, pictures and decorations from the fin de siecle and edwardian period.
Food was very good indeed, and was startlingly cheap from the point of view of visitors. The size of the veal schnitzel has to be seen to be believed and it is great value for money. There are lots of traditional Belgian dishes which are just yummy.
There is a fabulous range of Belgian beers, and for beer freaks, there are 10-12 beers on tap which are well kept, which marks this place out as serious about its beer, as all good Belgian places should be. The beer is expensive, though, (70-88 uar for 0.5L of most "mainstream" Belgian brands),more so than Belgian beer elsewhere in town - to the point where you would have to be serious about Belgian beer to go beyond your second glass. But with the food so reasonably priced, you can probably consider it!
The wine list is extensive and of good quality.
Staff were efficient and couteous despite the busy night and most spoke good English.
All in all, we had a great time and really enjoyed the lively atmosphere - we will probably go back a third time during our stay.