Well, I finally managed to watch this tonight. I had already seen a sizable amount of it thanks to YouTube clips, but I never really had the time to see it in full. I really enjoyed this special for many reasons - my favourite character being the focus was one, but I'll leave my bias out of this.
Sunset's situation of everyone forgetting that she changed and therefore rejecting her and giving her the cold shoulder, is something that really hits close to home for me. I empathised with her misfortune throughout and I think it made me love her even more than I did prior, as I just wanted to hug her. Trixie being an integral character of the plot, made things a lot more humorous and enjoyable than I had imagined. This special probably had some of the best gags in the whole of Equestria Girls thus far. I did enjoy the greater emphasis of the background characters from Canterlot High, as it gives them a lot more depth, especially compared to the earlier films.
I liked how they linked the plot into Sunset returning to Equestria, which allowed us to finally see her meet Princess Celestia again, after such a long period of time. Twilight freaking out in an adorable way was a bonus too. Wallflower Blush herself, was pretty "meh" villain. She had motive, though I still believe that she targeted Sunset only because she was the most convenient person to blame - I've been in her situation don't get me wrong, but still felt overly petty to me. Aside from that, I could relate to Wallflower fairly well, so that added some appeal to her character for me. Overall, Forgotten Friendship was well worth the time and I'm sad I didn't see it sooner.