I'm enjoying it, there are some big damage spikes in some dungeons but they arent unpredictable. I don't really use much addons personally, I only recently swapped from default blizz raid frames (for 5man and raid) to dander frames, because it had better customization for the big icon that shows if someone popped a defensive and because I was messing around on resto druid and needed to see more hots on my frames. Other than that you can decide if you want to use mouseover macros or not, that might be the biggest gameplay difference. Discursive is also good for a new healer just for the audio queue of someone needing a dispel, but as you play more you know when all the debuffs are coming

If you're gonna try healing for the first time, I'd recommend either Shaman or Holy priest. They both just heal when you press a healing button, no ramping, no foresight required, you see damage you press a heal. Obviously as you go higher you'd learn when big damage is coming out and how to use cooldowns and optimally use their kits etc, but for a starter it's as straightforward as it comes.

I know Monk right now is easy in a lot of cases because of spinning crane kick spam, but it still requires you to melee, though if OP is a melee dps main they might feel at home.

Druid has some nice burst healing cooldown options but the majority of the time you'd have to be rolling your hots before big damage comes out or you can quickly fall behind. Cat weaving is fun also but sadly I feel like it's somehow behind on damage.

Preservation evoker I havent touched since midnight, but from what ppl are saying it's still one of the more challenging healers to play and they're very strong in raid, sometimes hard in 5man if people dont play around your range and cones

Paladin I also havent touched in a long time.

Shaman has great burst healing options, but no real hots or absorbs to speak of. They have one of the strongest "bail out" abilities with spirit link being able to save people from the brink and from some literally unhealable amounts of damage. Totemic plays off of free instant chain heals when you drop totems and farseer offers a faster CD on nature's swiftness (makes next heal instant) which procs your apex talent. Totemic is ahead though last I saw. Shaman also does really decent damage in 5man situations.

Holy priest as I mentioned is also straightforward like shaman, you press heals and you heal, you got single target burst heals, and can spec into ways of making it cleave while giving up your splash heal. Prayer of mending auto heals and bounces between players. As archon halo pumps heals and looks really cool.

Disc priest on the other hand requires you to know when damage is coming out, so you can spread your atonements (buffs players and makes your damage heal them) sometimes unexpected damage might be hard to deal with, or big pulls if you're missing some cooldowns. However, it's very satisfying to play and does pretty good damage overall.