Assuming you did not get a procedural fairness letter (letter saying they plan to reject your application, giving you the reasons and giving you a last opportunity to address their concerns), DM on both sides =100% positive news. They finished processing your application. The only remaining thing is to invite you for the official landing.
Typically SA and AIP letters are received the same day or the day after seeing the change in ECAS. The DM letter is very unreliably sent; sometimes right away, sometimes with long delays (weeks), sometimes not sent at all! And even if you do receive the DM letter, the letter will only state that a decision has been reached (not stating which decision) and that your file will be transferred to your local office for finalization.
Now depending on your location it might take 1-6 weeks to receive your landing invitation. So, relax and enjoy your time, because in a matter of few weeks you will officially become a permanent resident!