I haven't used trakt and I'm not that interested in tracking TV shows, but I've been a letterboxd user from this winter and it's a great thing. It also seems to be gainging popularity and improving quality, bascially for me it is now the "goodreads for movies", which is kind of like a holy grail status for such a service.
I'm a heavy Kodi user and since I use both almost every day, I would be guaranteed to use a well-functioning Kodi-Letterboxd integration. I'm also a developer and may actually be somewhat interested in developing a plug-in if nobody else is doing it yet. I don't know Python well, but I have a little bit of experience keeping the Mubi plugin up to date ( my fork is
https://github.com/Villane/plugin.video.mubi ), which is of course quite tiny. In my opinion a good plugin would start by functioning in two main areas:
1) Keeping "watched" movies in sync between Kodi and Letterboxd. However, with letterboxd this is not always as trivial as it would seem:
Usually when I have watched a movie, I do not "Mark as watched", although that is a possible action as well. Instead I "Log or review", which logs a viewing, adds a date to it (I can change it manually) an optional review and a rating. I think it's so common to do this as one step that it may be awkward to just do an automatic "mark as watched". Would it be possible to pop up a dialog after the movie ends, maybe during credits roll? Then again, sometimes I want to think for an hour or two before I write a small review, so I might not even log it right away.
However, since a plugin should automate, maybe another acceptable flow would be for Kodi to automatically log it anyway with today's date (or yesterday if most of the movie was before midnight?) and later I could go and edit the log entry to add a review, maybe outside of Kodi.
Another option would be that the plug-in would ask me what to do at every movie ending: 1) Log (or review) 2) Mark watched 3) Do nothing (this could be default in case the pop-up dialog could be made to time out -- if I accidentally left a movie running or fell asleep then it won't be marked)
2) Letting me explore lists of movies. Letterboxd has a great feature in the form of lists, where you just put movies into a list and can add comments to each one. There are no separate notions of collections or anything like that, everything is done with lists. Lists can be public or private, and each user has a special "watchlist". It would be a really awsome feature if I could explore these lists in Kodi the same way I can explore movies in my library by various criteria. For that, I would like a quick access to "letterboxd" from the menu, and that would open for me a list of lists -- listing the names of my lists and the lists from other people that I have liked. Maybe there should also be a search for lists and I could then bookmark lists from other people. Obviously, from these lists I should also be able to play the movie if it's available in my library (and even more awesome -- play it from a service like Mubi, for example).
These two features would comprise of a functioning Letterboxd integration, to me. After this, one could think about how to bring the social features to Kodi and maybe bring more of the functionality of iOS app to Kodi. Maybe letterboxd could also be used for poster art -- it seems to have quality images for vast majority of films, although I'm not sure about rez.
