From poking around with IFTTT a bit today, Tasker is way more advanced in terms of what you can do with your device (settings, launching other apps, phone specific stuff) but the UI is very complicated and confusing. IFTTT's UI is really nice and has more integration with web services and popular social apps (Twitter, Instagram, etc), but the device integrations are pretty limited.

I imagine as IFTTT continues building they will add more device integrations - at which point I'd happily switch from Tasker.

IFTTT is more web+data oriented - e.g. sharing pics, location, etc. + actions based on them. Look at the featured recipes.

Tasker is for your inner geek to control your phone like you would with a shell script - volume, wifi, etc. to name a few.

IFTTT deals directly with hooks that web/hardware/data services provide. Think of it less of a tasker for your phone (linking events on your phone) and more of a simple tasker that links web apps/services(often without even passing through your phone). So, it will not have nearly the amount of control that Tasker has on your phone, but also does somethings that would be less possible or more complicated with tasker. Give this page a look to get an idea of the breadth of recipies: https://ifttt.com/recipes

Functionality-wise it's going to be far more limited, but I think for the things it can do, it will be much much simpler to set up.

Llama on Android also has a simpler UI and is Free opposed to Tasker.

I believe between Llama & IFTTT you should be able to do pretty much everything that Tasker can do.