Update
Moved the location of my feeder shortly after I initially set it up, so I could more easily see the activity through my kitchen window. I get a nice mix of birds... songbirds, cardinals, blue jays, a few downy woodpeckers, lots of smaller, colorful native finches, etc.
Except what used to be one or two squirrels has morphed into a bunch. So I bought one of these about a month ago.
I've yet to see a squirrel on it... I did see one feeding on the leftover seeds on the ground the other day, and he would gaze upward and look at it, trying to figure out a workaround I'm sure. He'll climb on the split rail fence right behind it, study the contraption, hop down, go to the base of the pole, look up at it, then run back to the fence rail, etc... I'm guessing he tested it out right before I tuned in and realized it wasn't an amusing, fun adventure hopping up there. lol
It's the same model as this one in the video below. Hilarious!