I did not enjoy this movie nearly as much as I had hoped. I did appreciate the depiction of Jackson Briggs as a vet suffering with PTSD and the daily challenges he faces from both society at large and as a result of his injuries (which, understandably he is in denial of).
What I found almost impossible to understand was his lack of respect for Lulu - and the incomprehensible need for him to call her "dog" instead of by her name. After all, Lulu was a comrade in arms who clearly was instrumental in many of his Ranger battalion's operations. The idea that he would appear to have forgotten, or cast aside all that Lulu meant to him while he regales in the past with his former human soldiers was ludicrous to me. I thought it also belied his keen interest to return to service.
I think the story could have been told in a manner that preserved the PTSD and other aspects of Jackson's suffering, and the challenges presented on his journey with Lulu, while being more honest with how I felt he should have acted around a former combatant.
The ending somewhat made up for it, but most of the time I was cringing at how he related to Lulu.