WHM remains good at what it's always been good at (raw healing throughput, which is overkill in basically everything in the game barring Ultimate), and lacking in what it's always been lacking in (no meaningful raid buffs, no meaningful mitigation options, not a lot of nuance to it.) SB didn't grow the class in any meaningful way, but the massive nerf to Balance + AST's pathetic personal DPS + WHM's raw DPS potency has floated them ok so far for prog. The raid meta will probably swerve against them again by the end of the expac, but we'll see. SB's relaunch of WHM was and remains a trash fire, but it didn't make them incapable of healing, it just didn't grow the job and was disappointing for anyone who wanted them to make SB WHM not just HW WHM with a couple extra buttons. The upside is getting level synced to 60 on WHM is considerably less annoying than the other two healers, since all the good buttons still work.
They're far more streamlined than the other healers, which means both that there's less to worry about and that there's more time where you're left throwing rocks because there's nothing more interesting you can do. EXDR is WHM territory by far, because Holy is the best dungeon mitigation in the game. Paired with a good tank you can basically wreck dungeons and get through super fast because you can destroy packs during the Holy stuns and have to do minimal actual healing. In 8 mans it's probably the job most prone to feeling boring, but whatever.
WHM's a solid starter healer, and if you do that and then want a few more extra buttons a lot of it maps pretty nicely to the Diurnal AST toolkit. SCH remains grossly overpowered, but accessing its ridiculous OPness requires a lot more situational button pressing than the others.
And targeting on controller for healer is pretty easy--up/down to scroll the party list. In raid environments I usually hard target the boss and then scroll up/down to soft-target party members to spot heal. Dungeons I'll usually go WHM, hard target the tank, and then just spam Holy forever. The only time controller healing is annoying is cross-group raising in 24 mans or PVP since it's using button combinations to target I usually don't have to deal with.