Assimil is also really good if you add the sentences/phrases of the dialogs and exercises to an Anki deck as you go along (flipping the card direction when you reach the "active phase"). The review gives you really high retention (and you can kill cards or the entire deck once you finish and get them to maturity).

If you want to use Assimil for a European language however, try to find the older "without toil" courses - they are so much better.