Personally I miss some features that were essential for me in the V2 of trakt. Here are the ones listed for me and I hope that the devs are taking a look at it:
Total watchtime
- The overall watchtime on the profile is an essential feature and I think that is what trakt is made for.
Actors / Guest Stars
- Actors of films and series should be sorted by main cast and guest stars again
- The number of episodes in which an actor has appeared should be displayed on the series tab
- on an actors profile should appear in how many episodes he appeared, not how many episodes the series had
Watchlist / Lists
- See how many movies/series are in a list
- The ability to see at a glance whether films/series are included in lists, not only watchlist
Contine Watching
- Sorting function in Contine Watching
- I’m missing the percent information in Contine Watching
- that you can see not only the missing episodes and watch time, but also the number of episodes and watchtime you’ve already watched
- The progress bar shows the exact seasons you have already watched (e.g. if you haven’t watched the first season, but the following ones, it shows this in the progress bar
Details
- Show us STATS! How many watchers and plays an movie / series / episode has.
I think that are all the features I recognize right now missing in V3, that were in V2.
There is one feature I would like to add.
Calendar
- upcoming movies from film collections (e.g. if a new part of a already watched film releases it should show in the calendar as well. I think right now you need to add them on your watchlist first.)
Thank you and hopefully I will see some of the features in the future. 
