They've made some changes recently, and specifically:
# We've simplified the user interface to make it easier, faster and more intuitive
# You can quickly refine or add filters to your query with an easy to use drop-down menu directly from the search bar
# By clicking on the "Details" button from any search result, you can now read an Abstract of every document as well as see the best matching portion of text from the document
# You can now Share your results to email, Digg, MySpace, Facebook, Twitter and other channels
# And, we've removed the registration and login requirement and are now in "open" Beta
If you're into doing academic research, and/or want to find content that might otherwise be lost or not even indexed by Google, give DeepDyve a go!