I think "this is interesting" might be a better introduction. Also, in my experience, when people (especially teachers and professors) say "this is tricky", it

I think "this is interesting" might be a better introduction. Also, in my experience, when people (especially teachers and professors) say "this is tricky", it is often in part or in whole because they are only giving you a partial explanation -- part of the picture. It's "tricky", because they are telling you to accept certain things prima facie when actually (for me, at least) they'd make a hell of a lot more sense and be easier to absorb with a more complete description/explanation. Some of the time, this is because they don't really understand the topic themselves. Other times, one or another pedagogical inclination or requirement makes them avoid a deeper discussion. ("I don't have time" or "We don't have time" or "That's beyond the scope".)