The new PDF abilities are rather basic. I've tested the app on my eeePad Transformer, and the only thing I can do with a PDF is pinch zoom, turn the page, and jump to another page. There's no typed notes, highlights, bookmarks, or TOC support.
Performance was okay. It was quite fast to turn the page and jump around inside a text based PDF, and the app also survived the PDF that Mike was using to crush an iPad. To be more specific, I was seeing page load times about the same as GoodReader displayed (8 to 15 seconds).That's actually a pretty good result, considering that this was a killer PDF made from high resolution page scans. The perfomance may have been poor but it was on par with the best PDF app on the iPad.
On a related note, there's no mention of support for Kindle Print Replica format. This is Amazon's own PDF format, and they use it for some textbooks. I'd half expected to see the Android app get support for both PDF and KPR, but that didn't happen. i tried a KPR file; it wouldn't load.
Like the PDF features on Kindle for PC, there's no mention of who did the code, but I suspect that it was Foxit. I'd gotten a hint yesterday that any improvements or new features may have come from them. But I'm also surprised that I got the hint; these features aren't worth much of anything. Remember, the Kindle app normally supports bookmarks, highlights, notes, and you can share content. You cannot do any of those things with PDFs just yet. I would have waited and claimed credit when the app could actually do something.
All in all, it's a good first step. It's also a sign that fixed layout is going to be a fixed feature in the ebook marker from here on out. When even Amazon caves and starts supporting the format in their apps, you can tell it's here to stay.