I've been using version 2.23.20 for a while now, and thought I'd give you some feedback:
I really like the fact that I can now see the total number of words in the course. It puts "my" number into a context. It's also interesting to see which words I've been shown the most (and how many freaking times!).
What I also really like is the new daily goal of doing one Challenge -- I have finally faced the (not so easy, for me) Russian Challenges. It seems that the little snippets of information you see after completing the Challenges are more related to what you were just tested on than the mostly unrelated but funny ones I saw before, which is really good. After all, you might have just stumbled through the Challenge.
The new daily goal of one Challenge has left me with only a handful of really hard ones left, though. So more Challenges, please! ;-)
Overall, the app seems to be getting better for every iteration, so I'm a happy Unlimited subscriber! :-)