I think it's pretty great myself.
I remember trying it out when it first launched, but I already have enough to play that I didn't want to continue subscribing.
Then the price dropped to, what $10 a month? So I resubscribed to play some PS3 games, and have been super impressed with the service. I'm actually legit surprised at how much content is available. Sometimes I think people don't realize how many titles are actually available on it. Being able to revisit Killzone 2, or Resistance 3, or the inFAMOUS games, has been great. And then being able to download PS4 titles I may have missed or had been curious about, but didn't want to buy at the time, is a really nice bonus.
If Sony and their partners would add more PS3 titles to it, it'd be an even better service. I'd prefer PS1 and PS2 BC to be native to the PS4/PS5 itself, but I'd also be okay with them adding PS1 and PS2 titles to Now as well. I honestly still think we will. We're still very early in the PS5 gen, so I'm sure they'll try to incentivize the service in the coming months/years. It's already a pretty great value to me, personally.