Google has newly redesigned the advanced search page and removed two options that weren't used very frequently: finding pages that are similar to a page and pages that link to a page. You can use the similar: and link: operators and "similar pages" and still obtainable in the Instant Preview pane, so the features haven't been detached.
What's disconcerting is that Google made drop-down lists a lot more difficult to use in the new border. Until now, you could use the tab key to select a list, but this no longer works. After clicking a list, you could use the up/down arrows or Page Up / Page Down to move among the options, but you can no longer do that. It was much faster to type the first letters from the name of the language or the country to rapidly find an item, but this is another feature that no longer works. Basically, the only way to use the new lists is to scroll up or down waiting you find the item you were looking for.
You can check the old superior search page at the Way back Machine or the advanced image search page, which still uses the old interface.
Another service that makes drop-downs more hard to use is Blogger. If you have a long list of labels, you can no longer find a label by typing the first letters.
Google Reader's new interface lets you use arrows to move among the items from a list, but you can no longer type some letters from a subscription's name in the "All items" drop-down. This was a non-standard featured extra back in 2007, when Google Reader added a search engine.
Hopefully, Google will address these issues and will no longer take away basic features that are taken for granted by many users.