I have used Anki for learning Spanish and Japanese vocab in the past and have found it very helpful.
Personally, I find it most useful when you make your own decks of cards. I make cards from vocab that I have come across in conversations/reading texts/listening texts and add them as and when. The good thing about Anki is you can convert a lot of "dead time" into useful language learning. For example, if you're sitting down for a few minutes waiting for the bus, you can spend a few minutes on your flashcards. You'll probably find you have a lot of moments like this every day and, if you get into the habit of using them to work on your flashcards, it will add up.
Plus, do you know Benny Lewis? He explains a visualisation technique for learning new vocabulary. If you're not familiar with it, it seems very strange haha, but I used it to learn a lot of vocabulary. Thinking of strange images and connecting them to vocab really helps them to stick in your mind and it's great fun. Well, it worked for me anyway.
Please let me know if you have any questions.