I bought the digital edition for PS4 when it was on sale, and have been playing it the last few days. I'm enjoying it; it looks great, and I like the way it really opens up stealth gameplay. So far I've completed the main mission and a couple of side ops; I think there's plenty of replay value if you're trying to get an S-rank on all missions.
For the side op where you take out two Marines, I went for the extraction route to get the trophy. That took a long time; I was searching all over the damn place for the second guy, and the intel reports I got for his likely whereabouts seemed to go out of date in about fifteen seconds. I thought it was funny how Miller said, "You're extracting the target? Okay, you can tell me why later." It's for the trophy, Miller! (And given the series' history of breaking the fourth wall, I feel like Snake could have actually said that to him.)
I just watched the E3 gameplay demo of Phantom Pain, and that looks really impressive. I'm looking forward to it.