It's a good example of a sweet spot between simplicity and power. Really IFTTT is a subset of pipes, but it's still "powerful enough" and the mental model is way simpler.

You could say it's 80% the power/usefulness of Pipes for most users, but 20% the complexity/learning curve.

Some of this is also down to the interaction design and polish too.

I'm a pretty technical guy, developer, etc. After reading your comment, I popped on over to Yahoo Pipes, having never really used it.

I didn't 100% understand what you could do with Pipes based on the first page. I still don't. Is it just for RSS and blogs?

I took one look at the Ifttt page and instantly understood what it could do for me.

Big difference in my eyes.

The first two times I saw Ifttt on HackerNews I went to their website and just thought it was a mantra of how to share information on the web. I thought they were just telling me that I should use Dropbox to upload files from my phone and then upload them to Facebook when I get home.