The Mexican American war did have long lasting repercussions that still affect the way the neighboring countries interact with each other. On some policies the countries will cooperate with each other. But many times the countries have differing views on major policy issues and this can set off a bad series of diplomatic relations.
Yes, i think that after this war we were a lot more at peace with Mexico, and that we were a whole lot closer to them as allies, since we got our fight with them out of the way and we settled all that we needed to have settled then.
I think the past is the past, so much has changed since then. I think the drug cartel and the murders, play a bigger issue. I really don't think a war that happened a century ago has anyone worried. It's been generations since that war took place, nobody even knows someone that fought in it.
There were some lingering sentiments about Mexico during the 19th century as a consequence of the war, but history shows that nations can just as likely become allies as enemies following warfare. Japan, Britain, and Germany have all been mortal enemies of the U.S., but are now close allies. There is no reason to presume that Mexico's relations with the U.S. are caused by a war 150+ years ago rather than by current relations and the drug cartel issues.
I think that while the Mexican-American war may have soured relationships for the decade around the war, I think overall Mexico and America have a strong friendly relationship in today's modern age, very few people talk about or consider the Mexican-American war when discussing Mexican-American relationships in today's day and age.