I am a very, very big fan of this idea as a way to engage users in a more meaningful way. A couple weeks ago I was actually talking with someone else on slack about this very idea, the ability to add non-voting reactions to posts as a different way of showing alternative kinds of feedback.
I'm guilty using emoji's like this on slack... a lot. But for as cheesy as it makes me feel to leave a smiley face or a thumbs up, it's incredibly useful feedback to the writer and other readers.
Back in the 90's and the super early days of chat/forums, the only way to respond was to actually type out the words, which floods the actual chat with repetitive information. This becomes problematic in a room with a thousand users all repeating "Awesome!". You even see this on steem today, with people writing "Nice post!" and "Interesting Read" - which just clutter up the interface and make it harder to read and engage.
Only within the last few years has 1st-class emoji support (lol, that sounds ridiculous) found it's way into our communication tools and social media. We need to embrace that.
As for linking the reactions into the voting system - I'm still on the fence a bit. I think there's a case to be made to leave them separate, and potentially even rename them it from "Upvoting" to "Rewarding". That's an entirely separate conversation though and I will try not to derail the discussion of reactions with it.
I am willing to be a part of whatever discussions are needed to make this happen across the network - and all sites that participate within the Steem blockchain. An open set of standard of reactions and UI/UX that users can use to even easier be a part of the community. It's something that I think is worth my time, as well as others.