I sometimes read old entries randomly, but rarely find it enjoyable. However, every New Year's Eve I skim through each daily from the previous year and make a list of "all the things I forgot I did this year", and the list always surprises me very pleasantly with lots of things I totally forgot about. Honestly this alone makes it worth journaling — I feel really bad about not being able to reliably recall things I did prior to 2015.
Looking at the entries from the earlier years, my writing has definitely improved a lot. I always write in English although it's not my native language. I also like to write on paper but it makes organizing the documents a pain.
To answer the question, yes it has improved my life and I don't plan on stopping journaling.