I think the Word Locker is just a list or notebook for problem words, as SWB suggests keeping in TWTM. HTH

As someone else said, it's very thorough with way more review than you will probably need. I actually go through every few weeks or months and circle excercises that I think are most important and note things which DS needs to copy (rules, charts, diagrams, etc). Then when I assign say pages 38-40, DS does whichever excercises have been circled. This extra step became necessary for me within the first semester or so of Language 3. We were doing 2-3 pages three times a week and I realized that we would never get through the book at that pace, but DS was (and still is to some extent) reluctant to write much and we were often ending the day in tears. Anyway, this was what worked for us. DS is now in 5th grade and has a pretty good grasp of grammar.

I have not used it but a friend who is a PS Latin teacher offered to tutor my son in Latin in exchange for piano lessons for her daughter. DS had already done Latin Primer 1 & 2. She ultimately decided on Cambridge for us, but initially she had planned on Ecce and let me borrow the books to look over. It follows a story and has some pictures. We're enjoying Cambridge but since I'm not teaching it I can't offer much about ease of use, etc. Good luck!