I've been regularly reading Le Monde since I was 14 (40 years ago...), and I share your view. The main criteria to assess its quality is the time devoted to read it and what I would call the "obsolescence delay" (i.e. the number of days you can keep it and still find the articles worth being read). Both have dramatically decreased in the last years. It might sound subjective, but I have found many regular readers who feel the same. I am a subscriber of the online version and I recently stopped to buy the paper version...
I find more and more that the external contributions (op-ed, LTEs) are the most interesting part of the paper it applies to Libération, too).
I nevertheless think Le Monde remains the French reference media, but you have to know that its standards are not as high as before and take what it publishes with a grain of salt (and, as said above, diversify your sources). "Dieu se rit des hommes qui se plaignent des conséquences alors qu'ils en chérissent les causes" Jacques-Bénigne Bossuet
Your obsolescence point is dead right. Le Monde used to have good things to read way after the twenty-four hours each issue covered. Now I don't often get the paper version, but if I do I leave it around. And find I don't go back to it.
i.e. their comments and in depth analysis pages have really improved, as their news pages have clearly declined a bit. In the long run, we're all dead. John Maynard Keynes
Do ou remember the front-page billet by Robert Escarpit? "Dieu se rit des hommes qui se plaignent des conséquences alors qu'ils en chérissent les causes" Jacques-Bénigne Bossuet
