I'm gonna be honest, I personally hate them. They're good for training and finding shinies but other than that... eh. But I'm probably biased, considering I'm in the minority when I say I actually disliked Sun and Moon. What about you guys?
Well, since their only use after the main game is to shiny hunt and/or EV train, I'd say that SOS Battles are amazing in that regard. Getting shinies isn't a challenge, just time-consuming (like most methods are), and you can EV train a Pokémon within 10 knockouts if you set up right. It was also an interesting battle mechanic for the Totem Battles, especially with battle combos like Totem Lurantis and Castform with Sunny Day, Totem Vikavolt with Charjabug to power up Vikavolt with the Battery ability, and Totem Kommo-o with Scizor to defeat any annoying Fairy types.
I agree with this. Though, I will say it tends to get annoying when you're actually trying to catch one particular Pokémon, and they constantly summon more of them to stop you from throwing Pokeballs. I've had this happen way too many times.
I think SOS battles were a fun mechanic for Totem Pokémon to use, but downright annoying for regular encounters. There are a few interesting things like having Sableye show up when a Carbink calls for help because it wants to eat Carbink's crystals. But those small tidbits weren't enough to save the mechanic for me. I would have rather seen a return of old features such as horde battles and/or DexNav.
I think they are pretty alright, that's what made the Totem battles a challenge (At least to me anyway). However, I don't really like the fact that if you are trying to EV train then doing SOS battles is the fastest way. I like to this that SOS battling replaced Super Training for the most part.
I'd rather have SOS battles over Super Training, but horde encounters over SOS. It's more entertaining to watch five Poochyena keel over, one by one, as your huge dragon Earthquakes them into the ground. *realizes how that sounds* I mean...it gives you more XP sometimes? #MissingNo
