Love the language and found it quite a joy to learn and use. Written a few little scripts with it and as a learning exercise I took defunkt's ike (http://github.com/defunkt/ike) and refactored and added features to it.

However the implementation has caused me some headaches. For eg. some of the Addons have dependency issues and I could never get the VM to compile at all on my Apple Powerbook (PowerPC). Also be the VM is very slow (for an example it is slower than Ruby 1.8).

But overall I came away with positive feelings about Io and I am definitely keeping my eye on it.

Here is a fun FizzBuzz I wrote:

    for (n, 1, 100,
        fb := list (
            if (n % 3 == 0, "Fizz"),
            if (n % 5 == 0, "Buzz")) select (isTrue)
    
        if (fb isEmpty, n, fb join) println
    )