As a healer main, I have been bringing Rescue since long before 4.4, and I've always found it useful for saving people who make mistakes, or in other more niche cases, using it to cheese mechanics.

However, it really does have a bad rep, and if it's not some heroic Rescue, you're likely to get flamed for it. Sometimes I pull someone at a terrible time and end up wiping the run, although this is quite rare. More commonly, I may cast it slightly too early to save that DPS that looks like he's about to get wrecked because of greed, then he flips out when he loses 1 GCD because I rescued him. It's a pug though, so I don't always trust my DPS. Especially when they're always dying.