I was under the impression that the screw holes are standardized when it comes to speakers, but apparently Celestion and Eminence speakers don't have the holes on exactly the same spots, as I've learned by trying to install a new Eminence speaker unsuccessfully and then doing a quick search on the internet. I'll be keeping the box anyway, I kinda installed it forcefully and ruined the holes a bit; the speaker is holding on so far, but it's obviously not the best solution. I might try to drill new holes later on (although the terminal wires running from the cabinet seem a bit short, so they'll have to be very close to the original ones), or I'll close these existing ones with some wood and wood glue and then drill them again, I haven't really decided yet. Anyway, if you're planning installing Eminence speakers in it, you should know what you'll be dealing with.
When it comes to the features and quality, some more precise instructions for connecting the speaker and the cables would be welcomed by the less experienced, especially because the colour of the wires in the cabinet doesn't match the ones featured in the instructional leaflet you get with the cabinet (there's a black and white wire in the cabinet and black and red in the diagram of the leaflet). When it comes to the quality, you can't fault much for this kind of money I guess, but I think it would be better if the speaker was attached to the cabinet with some nuts and bolts, than with a screw (as another reviewer also commented), the speaker would be much more safe and stable.
I've bought an unloaded 1x12 cabinet by Palmer at the same time, it was a bit more expensive but I can already see the cables in that one are of the higher quality and it would be the one I would personally choose between the two. I haven't tried to install the Eminence speaker in it yet though, but presumably the issue will be the same.