It was very much on-the-spot most of the time. I was asked at one point, after given a blank piece of paper for metaphorical reasons... "If you had this job, what would you do?"
Caught me off guard and that in turn made me look foolish. Not a great experience to be put on the spot with such technical questions so early on. I was told this wouldn't happen on the 1st interview.
I was also declined the job, told "not enough experience" even though they saw my CV before agreeing, enthusiastically, to see me?!