Definitely by far the best way to learn to write characters. It is very expensive (compared to most apps, anyway) but its essentially obligatory to spend the money if you are serious about learning the language. When I'm learning Mandarin my favoured method is to work my way through the HSK decks on Skritter, plus a custom deck where I add my own words. Then I make sure to put at least 1 example sentence in Anki for each word that I've learned in Skritter, to reinforce it and place it in a useful context. Skritter itself rather helpfully gives an example sentence for most words. This often then leads me to adding more words to my custom Skritter deck when the example sentence contains other words I don't know yet. In this way I expand my vocabulary beyond just HSK.