My friends tried to dissuade me from applying to Oxford--they warned me of the academic pressures, and said that I wouldn't enjoy my time there. I applied anyways because I like a good challenge, and I'm so glad I went.
During my two terms at Oxford, I took my primary tutorial in math, and my secondary in French. I didn't love the tutorial system for math, since I would've liked more lectures and peers to work with, but tutorials worked incredibly well for French. Reading so many dense texts and synthesizing my own ideas gave me the confidence to pursue a French thesis my senior year. I actually ended up writing a thesis in math as well, since I felt confident in my ability to tackle independent study after Oxford.
The campus/town is so stunning, so walking around always lifted my spirits, even when I was stressed. I loved my living situation, though it was a bit far (15-20 min walk from my college). I was put in a house with other international students, and we grew very close. I didn't actually make any good local friends due to the independence of the classes and my living situation, but I still stay in touch with my visiting student friends. I did participate in the Oxford University Orchestra for one term, and did a few practices with the triathlon club. One thing to note is that clubs always cost extra at Oxford, and membership to the main gym as well.
I would highly recommend this program--IFSA really makes sure you're supported and plans many fun events. Andrew, the director, would visit weekly and meet us for tea and pastries or ice cream. There's also a wonderful trip to Lake District, which is such a stunning mountainous region.