I knew every one of the Beatles songs immediately, but I was typing so fast over existing crosses that I somehow ended up with PAPEpBACKWRITER (55A: Author's favorite Beatles' song), and it took me about two minutes to find the mistake. Oh well. Haste makes waste, as we all know.
Kind of an odd puzzle today. I like the Beatles, and as I said, I know all these songs, but all of them are now very nearly fifty years old. And are they worth the crosses? Just look at the NW alone, where we find SYST, LEHI, ELEM, and POL. Continuing on through the downs we have SUVS, OBIS, BIOTA, SEEST, SAUR (!), RHEUM, BMWS, RUHR, AVILA, LUXE, QUAYLES, BRYN, NBAER (yuck), ABOY, ITSO, NEUR, and ERNS. And I didn't even mention the odd-looking duplication of FOR and FORM. In my book, the price is too high. Everywhere you look, there's something off-putting. SRA, ARI, AYES, IRS, ETAS. GRR!
The one bright spot, so to speak, is GALILEO (21D: Astronomer who discovered the main moons of Jupiter). And GROWTH (42D: Expansion) isn't bad.
It's kind of special, I guess, to get five fifteens on a Monday, and the little FAB FOUR off to the side is a nice touch, but too much had to be sacrificed, I think, to make this work.