I just started using Duolingo a week ago and I'm loving it. I do sometimes have problems with understanding the difference between "il" and "ils", "nous" and "vous," but I have trouble with that in face-to-face learning. I can't blame the app too much. I have a seven-day streak going currently! My big problem is I took five years of junior high and high school French, and then I took three semesters of German in college. I keep crossing vocabulary. Hopefully the app will help me sort that out. (What is French for "the app," anyway?)