Okay, I'm not very impressed at all (note that this is my first impression).
First, I'd like to take control over how the "camera" are positioned in the 3D desktop. I'd rather prefer a position that "stands out straight" instead of "rolling your head back" just to look at the picture of a Flickr frame (never used Flickr). I've removed a couple of junk (except for my icons and the picture frame in the wall) to clean up the desktop area.
Second, I didn't see a way to change the look of the wall. I assume it's in the "more options" when I right-click in the empty area of the wall. But I can't bring this up, which leads to the last part of my first impression.
Last, but not least, selecting "pile by type" or "more options" does seem to hide the dialog behind the BumpTop, which tells me it looks much like an application than a shell, like the explorer.exe shell for Windows or GNOME or KDE shell (I know it's just a desktop environment) for Linux. IMO, it gives me the impression that I'm running a beta version of BumpTop and there are some bugs that still need to be worked out.
So, with my first impression out of my way, I'd like to go through not-so "awesom stunt" features.
Sticky Notes -- I'd prefer to write down tasks in Outlook, but to each their own.
Toss files onto USB keys -- Not so awesome. It's just like when dragging files to a USB drive that is in "My Computers" explorer or when using Linux, such as Ubuntu.
Most used files automatically grow -- Who cares?
Flipping through Piles -- Again, who cares? I'm not that cool to have so much of bragging rights...
Thumbnail Previews -- No big deal. Note that I've not taking fully advantage of BumpTop, so I'm not sure how noticeable they are.
Customer Support -- Forums, anyone?
The price of BumpTop has -- no value to offer for me. In my opinion, it'd probably belong in a Mac instead of Windows -- for those who value bragging rights and coolness more than anything. Me? I'd take a boost of productivity anyday and get my work done, even though I'm just a computer geek.
To summarize my thoughts and opinions, here's my question and my answer: Would I recommend BumpTop to someone who loves to work with 3D desktop? No. Even though there are some who'd like to have bragging rights and be cool (even in Windows), I don't see how much value they can get out of a $30 software. I'm just trying to be wise, though.
Update as of 11:32 PM EST: When I uninstall BumpTop, a web page in Firefox came up and it gave me a welcome to BumpTop Pro. Huh? I'm confused since I've already uninstalled it.
As an addition to that, I saw "Your BumpTop key is" but it does not give me the key. I couldn't remember what it said.