So, I saw all of it except most of the prequel episode (because it's too hard to watch Starfire rampaging as the opposite of what she later becomes, and she probably doesn't reform until the end) and the final episode (because it's pointless in opening up a mystery it never resolves, we don't even know for sure that is Terra).
I was directed towards this as a show focusing on these characters that I'd find appealing. It's cleaner than Teen Titans Go, lighter than Titans, has many entertaining moments, and one of the main villains dies (Trigon, the most menacing), that's always helpful in making an animated family-friendly show appealing to me. Two if you count Slade, he got revived from his fall into the lava and may or may not have been re-killed when all Trigon's magic was undone, since it was by Trigon's power he was resurrected.
And most of the other villains get frozen forever. Brother Blood just gets arrested like most MotW's, except somehow he never seems to escape. (must be his lack of arms) And while he did feel compelling he also seemed the least threatening. At least compared to Slade and Trigon.
So I started with Season 4 to get an idea of what the show is like, so I wouldn't feel impatient to get to Trigon, and to get my first impression from the season with my favorite type of villain defeat. Suffice to say it was good enough to watch the rest of the seasons.
Favorite character, Starfire. She's always fun to have around and I'm really annoyed they gave Beast Boy two seasons and Starfire none. She's the only one that didn't get a season (the one that SHOULD have been her season had her absent for a lot of episodes!), and her archnemesis is only the villain of two episodes, unlike the other four archnemesi who are each main villain of a season. (I probably wouldn't like any of her favorite foods though)
Favorite main villain is probably Trigon, favorite MotW/recurring villain is Control Freak.
Although, while Teen Titans is cleaner than Teen Titans Go, it's still not 100% so. (But neither is MLP: FiM) They seem to take great care to avoid p*nty shots with Starfire - I always respect any show that has girls with miniskirts in a prominent role and avoids that, Inuyasha being another example - but I think they slipped up with that in the second episode. (I heard the MLP spinoff with human ponies did that too once) There was also a suggestive moment with her involving See-More's X-Ray vision. (I infinitely prefer her outfit to her comic counterpart though)
While Beast Boy on numerous occasions makes me wonder if he's meant as "fanservice" for the female viewers, there are quite a few suggestive moments with him that made me more uncomfortable than any of the Starfire ones even. (of course I'd have liked it even less seeing her in any of those moments)
On the flipside, me having an interest in tails he is also the primary source of tail play in the show. Though we do get a bit from Starfire when she turns into a tiger.
But another thing that rubs me the wrong way is not giving a definitive conclusion to Slade, and while I knew going into it he'd fall into lava and get revived, where is he now and why is he absent from Season 5? I'm going with my above theory, even though Raven, who would be his re-killer, speculated Slade got away. If he is still alive, this is what I was afraid MLP: FiM would do with King Sombra in Season 9. But fortunately Sombra was re-killed permanently.
When it comes to undoing what Terra sacrificed herself for (the volcanic eruption she used all her power to stop was a result of the power she used to defeat Slade, and I really like lava villain deaths), I wish they hadn't killed Terra at the end of Season 2, I'd have liked her to stay with the other Titans. And even if you think that was her in the final episode it served no useful purpose to have her in the final episode with no memory or power.
Only two episodes I really disliked besides the above one were "Crash" and "Hide and Seek." The rest were really entertaining, especially Control Freak or Mad Mod episodes, and the Mumbo episode where he turns them into animals. (On a side note, Mumbo looks like Beezen from G1)
All in all, the good outweighs the bad and it is one of my top three favorite DC series (other two being the Tim Burton Batman films - including Batman Forever but NOT Batman & Robin) and The Flash (don't really like much else of Arrowverse))