My wife is Chinese to I use WeChat a fair bit. I only use it for messaging and calling, so can’t comment on the other features, but for what I use it seems fast, stable and easy to use.

How do you distinguish between featureful and bloated? What are the criteria you would use to tell one from the other?

Personally I don't think it's too bloated. However, its an absolute storage hog ~ My WeChat is taking up 2.4gig of storage space. I guess thats the issue of audio messages alongside the ability to send full-quality images.