I had a very nice glass top cocktail table about as big as you describe and wanted to get rid of it due to a total redecoration of the living room. First I went to a consignment store and they would not take it for any price, then I advertised it on craigslist for peanuts, not once but about three times, no one called. Finally I donated it to Goodwill who was nice enough to come to my house and pick it up. So I guess you could say it is dated as no one wants them anymore, but if you like it and it suits your decor, keep it. I got a 5' rectangle ottoman and it is so much more useful, but these pieces have to fit your style.

There are a lot of companies still making glass coffee tables, so they must be "in" with a lot of folks. You could also use some water based antiquing glaze on your brass if it is a bit too bright and give it an updated look.

Personally, I REFUSE to base my furniture choices on what people tell me is in or out. Why should you shell out money to replace a coffee table that you want to keep just because your friends are ruled by what is "in"? That is ridiculous! My philosophy is, if it is in my house and I am happy with it then it must be an excellent piece of furniture. If someone else criticizes it, I just assume that they do not share my excellent taste. :-)

Oh, I hope you kept it! Brass is back! And those tables are selling for a thousand dollars or more on Chairish and similar sites now.