We were using smoothmoves in unity for animation of our 2D aliens. It worked but the workflow was very slow. example of an idle animation using it:
The results were workable but it took a lot of art tweaking to cut up the characters just right to not notice the seams when animating. Also because of only being able to scale or rotate each body part, we were very limited w amount of movement before seams were obvious. I picked up puppet2D for unity and it supports bones/IK and mesh deformation. Great I thought... well after two days of messing with it I just couldn't get it to do what I really wanted, which was to speed up my workflow. I spent forever with a single rig trying to get the IK system to work right w more than two bones and then when I got that sorted I spent forever manually setting per vertex bone weights.
The end result... a bit more funky than what I already had but just in different ways. I was about ready to go back to smoothmoves but saw uni2D... so tried it and within 10 minutes or so of rigging I had something I liked a lot. It will also speed up the workflow a lot since we won't need to cutup anything that doesn't overlap another sprite. It has a great system to make a mesh sprite and auto grid the mesh w #vert/horiz points. then you can simply click some bones on top and it morphs the mesh very well. This is an exaggerated example of a quick animation so you can see how it warps the mesh feeling very organic. We couldn't have moved the neck/arms/face nearly as much with the old system without seams showing.