Is the Philter of Love a NO save charm monster? The potion states, "The next time you see a creature within 10 minutes after drinking this philter, you become charmed by that creature for 1 hour." It also does not seem to have any of the drawbacks. As a RP tool for a character who is an alchemist or poisoner, this could be gold.

I guess if you can somehow convince the monster to drink it, sure. 

I guess. They do have to drink it though. Like the whole potion, not just pouring it into a watering hole.

 There --IS-- a slight difference between the philter of love and charm monster.  While both inflict the charmed condition....

Only Charm Monster says that the target is friendly towards you. The love potion makes a being that matches certain criteria to fall in love with you (assuming first to be seen, etc). The overwhelming majority of the time, any random monster won't be sexually attracted to your race/gender. 

The charmed condition has been used for multiple spells and abilities, such as hypnotic pattern, that have nothing to do with making someone think favorably towards you. So, its extremely possible to have someone who's hostile or indifferent charmed. Which can have other implications, depending on how the DM runs things.

Assuming you can get/force them to imbibe the potion, it is still no save, they are just charmed. If they happen to be lecherous to your kind, you also have the benefit of them falling in true love with your character. The idea of TRUE love could be bent by a GM to almost anything from toxic masculinity to honest compassion with no boundaries or lies depending on the character of your target and GM. Also, I know charm in 5E is not super powerful, but in a RP world with advantage and a social character, it can let the players set up some powerful scenarios.

I never even knew of the philter until we received it as treasure. I am a halfling, warlock/swashbuckler, face character that is a hard-as-nails, noir detective. In a previous session, my character was in awe of a polymorphed dragon which granted us a favor. My favor was for her to take her natural form and hit me with her fear because my character lives for simple pleasures instead of gear and I passed which impressed her. I managed to social my way into her good graces and kept things civil although the table thought I was trying to hit on her. Fast-forward to many games later, we are trying to stop the next big bad situation and during the conflict, the dragon returns in a raging manner. Our group is more about conflict resolution than leaving red, sticky floors everywhere, so we all start scouring our stuff to see what we can do without harming her. Our cleric whips out the potion and tells me to toss it in her mouth and hit on her. None of us had actually read what the philter did because it was a forgotten note on our supply list, it was just a desperate, silly act. I succeed at my improvised weapon attack and almost get chomped in the process, then end up riding the side of the dragon's head, the GM did not make it easy. We looked up what the potion did and the table asked if 'way back when' she might have thought of my halfling as being of possible romantic interest and the GM gave it to us. I was rolling very well on my social skills the last time we met her, it was a funny night of RPing. GM decided to allow it and now I have a no save, love charmed ancient dragon under me. We just calmed her down, had her stop destroying the city, and took her to a safe place after she polymorphed into her fey form. After that, the GM and I realized how strong the potion could be.

Careful that is  how centaurs started.

Quote from theHumanChris >>

As a RP tool for a character who is an alchemist or poisoner, this could be gold.

 Only if you can find the recipe for it :-)