I use spanishdictionary.com (both the app and website) all the time for when I forget a word or conjugation, I really like it for that. The fact that when I type in a word in either language and hit enter, it goes straight to the page for the definition and translation to the other language is great UX (i.e. not dumping me to a search results screen, or making me toggle between languages)
I think it got me to try out a lesson a while back but it felt kinda half-baked and I never continued further.
My biggest issue with the site/app is the constant splash-screens/pop-up modals that take over the app/website to try and get me to upgrade. I get you guys want to funnel people towards the subscription, but being nagged daily when I'm just trying to look up a word is not making me more likely to bite.