I've got several remarks.
In the "Visitor details" screen, the filter is always set to "Everything".
It doesn't stick to the value that you assign it (generally in my case "No spam, no spider"). This is pretty annoying.
Also, you don't get the same information in the "Visitor details" as in the "SPY visitors"! In one case, you get the language, operating system and browser type, in the other case, you get geolocalization informations (flag, country, city). Would it be possible to get all these informations whatever the screen? This would make comprehension really easier!
Finally, why do you limit the lines available in the "SPY visitors" screen? It would be good to go at least one day back (if this doesn't consume too much space).