Really not one of the stronger episodes.
"The Super Speedy Cider Squeezy 6000" sure starts strong. A lot of great humour and a brilliant song? Seems fun. But things do downhill when the episode actually gets to the point where a conflict is introduced. This episode is somewhat entertaining, but has a distinct refusal to actually feature any sort of complexity. This is a flaw that it could never hope to recover from, but despite that it's not terrible.
The Flim Flam Brothers are very entertaining characters. Let's get that out of the way first. From their song to their smug attitudes, their screen time is a consistently good time. Indeed, said song is one of the catchiest and most fun of the season, and it's one that I find myself repeatedly coming back to. These characters have an air of shadiness, but they wear it so smugly on their faces that they're hard not to like.
However, even in the excellent song things start to move in the wrong direction. Granny Smith immediately takes the mere existence of an alternate cider source as a challenge, and appears personally insulted by this. Now, this would be fine, if more sensible ponies just ignored Granny's argumentativeness. But it's the general attitude of the episode at large. There's potential conflicts introduced-innovation vs. tradition and integrity vs. desperation shine through, but the former is basically ignored and the latter is rushed through.
The episode includes Flim and Flam making the Apples an offer, and while it's not a terrible one, it's not enough for the Apples to sustain their farm. They don't even look at negotiating the price, and while that's not a particularly horrible thing in and of itself, but Granny's offence at the Flim Flam Brothers causes her to risk the farm. Again, this could have been an interesting conflict as Applejack had to decide whether or not to support Granny, but instead it just served as an excuse to make Flim and Flam take on a generic evil corporation role.
That, ultimately, makes this episode disappointing. Maybe the writers should have made it more complex, or maybe they were in over their heads, but what we're left with is an episode that is entertaining enough to watch, but really doesn't move the show forward in any way and offers a simplistic narrative on top of it. Not the worst the season has to offer, but certainly not the best.