Depends on what are the intended uses for the machine. If it's a main source of entertainment, information and work/hobby use (in other words: my computer is only thing I use to play, watch tv/movies and work) then 250 GB is not enough.
In that case extra 24GB means place for either pagefile only or pagefile + hiberfile. I would give a lot for that extra 24GB right about now.
If it's basic family stuff (email, browsing, photo storage, some text/spreadsheet once a year) - no point bothering with it at all.
NO point using it as cache - the idea behind the setup was to essentially create one hybrid drive out of this SSD cache and normal HDD via Intel Smart Response Technology. No point (counterproductive, in fact) to keep this caching with SSD.
Source: hands-on experience of last 6 months. Given chance I would ATT fork out extra to have at least 500GB SSD. And which I may end up doing. Also, I may end up buying this 500GB SSD in m.2 format...
Explanation: I thought I can keep up with 250 GB SSD and USB3.0 external 1TB HDD. Worked up until my daughter figured out that "pulling at this weird black thingy makes funny noise and after that it's perfect teether, while shiny box at the other end is a nice toy to throw around". So at some point you may want to keep everything internally and still have DVD burner to do hard backups of photos, movies and docs, thus HDD in ODD bay is not so great idea (still cool, though). And it simplifies life if you are mobile a lot - more than once I found out that while me and my laptop was here, my external HDD was elsewhere.