Nice shot and smooth BG, on my screen the colors are a bit mute and can benefit from sat. but it may just be my scree. I'd prefer more sharpening on the feather and head. Eye contact is a plus.
Vireo's have that fine feathers almost like waxwings, I use smart sharpening in photoshop with an amount of 40% and a radius of 0.3 IMO no more sharpening is required and is probably a personal taste thing. This was not a setup but a perch of his choosing.