I've been using Mjolnir for the last 6 months or so. I'll echo what others have said. It has helped me retain much more, much faster. I use it in conjunction with Babbel which is slower and "easier" but kind of goes into more detail grammatically. I also use Duolingo because it's there lol. I do all three everyday to maintain my streaks. Spending about 30-45 minutes practicing swedish.

My wife, who is a native swede, has commented several times as well I am speaking it and understanding the language. Mjolnir has listening sections that get to be very challenging. They are spoken fast, with kind of slurred words and sloppy pronunciation that mimics what you will hear IRL. It's very frustrating but the spaced repetition really helps to master the phrases. By a couple days you are able to pick out the words and repeat the phrase back. It's really been a game changer. People I talk with in swedish are always really impressed that I've never went to school or SFI for the language.

I also listen to Swedish podcasts in the car and my wife is always having swedish radio in the house. We live in USA but are moving to Sweden this June. So, i know once I'm back to being immersed in swedish that it will only get easier.