Ask HN: Is this captcha concept any good?

I was reading the post about Minteye and was reminded of a simple captcha I wrote a few years ago.

Here is the image generation part (the full implementation requires the two words to be entered in any order): http://humbit.com/snippet/captcha.php

I've seen some really hard to read captchas in my day. Even reCaptcha often gives me problems. I've always thought this one was very readable. It also seems to be fairly secure for the following reasons:

-text is not in a straight line or even in an exact circle

-the font is not very distinctive. most letters looks similar

-as much as possible, I've jammed the letters together to prevent easy segmentation

I have a few ideas for improving it and maybe releasing it as a free service. But is it actually good enough to make it worth pursuing? I'd be content with someone pointing out why my thinking is flawed here.