The tooling(?) (starting with xcode) is quite objectionable and is enough to drive people (me) away. The language choices are well. Interesting. Kotlin fills the need for mainstream Swift better than Swift, and without all the baggage that Apple brings to the table.

If you want to see what open source Swift is going to end up like, just look at GNU objective C. It will likely follow the same pattern of adoption over time and be hobbled on non-Apple platforms.