I didn't really find the bosses difficult to begin with, so I can't really comment on what difficulty to look forward to, but...
For the Dragolich, be VERY patient. Rushing things will get you very frustrated also.
Against the Silver Knight, the fight can be very intense because of the constant need to switch magic.
Likewise, with the final boss, the need to switch magic remains. However, at a couple of points, you have to walk through circles in the ground with a certain type of magic, and this part is just annoying.
Other than that, though, yeah.