I've only started playing around with themes for the first time today, but so far this is one of the best themes!
There are only a few problems, mainly in some extension configurations, that are hard or impossible to read due to black text on black background. One of them I've notice is 'Lastpass' - for instance, the group box doesn't show - although you are able to use the selector and see what group you are selecting, it wont show in the box unless you highlight the text. Another is 'Session Manager' - for instance when you go to manually save a session, the area where you select which tabs will be included doesn't show the checkmarks next to the tabs to be included - unless you select a tab and then the checkmark will flash white. Fortunately these aren't major problems as I don't really use the session save feature to de-select tabs when saving, and I am able to work around the group box of Lastpass. There may very well be other problems like this with other extension configuration pages, and I remember having a couple others but can't remember which ones. However, this theme is SOOOO nice that it doesn't dissuade me from using it. Hopefully these issue will be ironed out in the future.
There is also another bonus which doesn't directly involve this theme, but... I have a problem between 2 extensions that is in a delicate balance to have one of them work properly. The problem is between the 'CoolPreviews' and 'Tree Style Tab' extensions.. Under certain circumstances, the CP ext. will cause TST to display the url in the tab instead of the title if I don't want to load all tabs upon startup (which I don't) - it can be a delicate balance as I say. However, when that problem crops up, all I would have to do to correct it would be to disable CoolPreviews. I do notice however that TST is listed as being preliminary reviewed by Mozilla, and I believe TST IS in beta - but it's too nice now that I've finally started to get used to it. (Seriously, *scrolling* to look for a tab!! I don't know how I put up with that now! ;-)
Well -- I've been noticing that many other themes will upset this delicate balance and TST is too nice on my widescreen monitors(2 laptops) to not use. This Blue Fox theme is one of the few that doesn't upset this balance! It also doesn't force all tabs to load upon startup like I've noticed some themes will tend to do (The others may just change the setting, but if they do that then I likely wont want them anyways if they're that pushy about it.).
So, all in all, I give this 4 stars. I would have given 5 if it weren't for the issue of some dialog boxes being hard or impossible to read - as well as some toolbar/add-on bar buttons. Hopefully these issues will be ironed out though and I will eventually be able to give it 5 stars.
A VERY NICE THEME INDEED!