I don't hate Season 3 necessarily, but IMO it was the low point of the series.
Episodes 1-2- Sombra was a poorly developed villain with basically no screentime, and the episode itself was quite forgettable. In fact it's the only series premiere that I sometimes forgot even existed. Even S6's premiere was one I remember because it's the only episode I never watched (because the premise just sounded like it would make a bad opening). Episode for me was about a 5.5/10.
Episode 3- Probably the highlight of the season, though Pinkie Pie, even considering how many of her there ended up being, was a bit more annoying than she should have been here, but I have few problems. About an 8/10.
Episode 4- Introduced Babs Seed, my second least favorite character to have been part of the Cutie Mark Crusaders. She was downright rude to the CMC and basically seemed to torture the CMC... for the sake of doing so. Episode felt as if it had too little effort put into it. A 4.5/10.
Episode 5- This episode existed purely to give Trixie more screentime apparently. Seemingly out of nowhere she decides to harass Twilight and stroke her ego some more. A 5/10.
Episode 6- The episode where poor Scootaloo has a nightmare. It was a decent episode, but I find it as unmemorable as the premiere honestly. 7/10.
Episode 7- A fairly decent episode with a decently-written plot behind it, but I didn't like all of the drama. 7/10.
Episode 8- There was so little to this episode, that was apparenly about an Apple Family Reunion. All I really remember at all of it honestly is "Raise this Barn" and honestly it's not anywhere near the best of the series in that regard. 6/10.
Episode 9- YIKES. A Spike episode already plagued by a cliche premise, that becomes probably the worst Spike episode in the entire series. He became aggrivating and downright annoying. It was so bad I could SWEAR Spike suddenly became a different character. Probably one of the worst episodes of the entire series. It's up there with the finale of this season as well as "Hard to Say Anything." 3.5/10.
Episode 10- Pardon my wording here, but how can an episode with Discord in it be this lame? Working with the master of chaos himself, and you make an ENTIRE episode dedicated to reforming him. Actually pathetic Hasbro. About a 4.5/10.
Episode 11- After the miserable failure that was Spike at Your Service, they do ANOTHER Spike episode. One not even much better than the last. Premise was clearly an excuse to give more runtime to the Mane Six's pets, and the episode was ANOTHER bland episode in itself. Not another Spike At Your Service, but not really a good one either. 5/10.
Episode 12- Even Dave Polsky agrees when I say this, but the ending to this episode made NO SENSE. Doesn't help that this is another stale episode with relatvively slow pacing that makes it feel like it's dragging on for twice it's runtime. Another 4.5/10.
Episode 13- I really, REALLY don't feel like talking about this rushed sloppy mess of an episode, with a conclusion that made so little sense that a vast majority of the fandom was just absolutely DUMBFOUNDED. Pacing was WAY off, none of the songs really resonated at all (in fact I just wished they STOPPED), and the ending was the most nonsensical, clear attempt to end any series I've seen... At least it didn't cut off there and the ending did something GOOD by paving the way for mostly good seasons thereafter. Nonetheless, it was a complete dumpster fire in my honest opinion. A 2/10, worst episode of the series in my opinion, even over "Hard to Say Anything."
Basically the season is full of bad or unmemorable episodes, with literally only 4 episodes I'd consider decent.
EDIT: After a revisit, well, I've further soured on it...