- The UI design is visually distracting, bulky, complicated. There's too much going on at the top, 3 differently colored bars with the powerset logo, tab(s) and huge search bar. The search bar is omnipresent, even in the individual Wikipedia page you chose. Ironically, Google has a similar structure in its result pages, but feels completely different because the background is all white and less invasive.
- The Factz are often distracting and presenting useless stuff. E.g.: http://www.powerset.com/explore/semhtml/Simple_DirectMedia_L... presents around 25 factz. I counted 3 or 4 factz that are actually useful. The meaning of the other factz in the context is either obscure ("parameters": which ones?), deceiving or incomplete ("functionality", "ports", "operations", etc), useless ("needs" (??), "SDL", "The Video"), or all of the above.
- The way you actually use the Factz is terrible. First you clik on one fact, then after being flashed with the fade-out bling on the right column you actually have to move the mouse pointer all the way there, then the animation scroll, then probably move the pointer to the left to click on something actually useful or go back up to select another fact because the one you chose was wrong anyway (why? see above). After 5 minutes of this I feel dizzy. Who designed this stuff?
- massive waste of screen real estate with large white space on the right column, either entirely (results page) or partially (actual wikipedia result page you selected).
I do think there are some cool things, but so far it seems hard to use IMO.