Let us all be grateful that Bujold quit and Mulgrew got the job instead.
I haven't seen Bujold in any other movies or series so I can't judge her acting skills. Maybe she is a very skilled actress. But I don't think that she was the right person for the role of Janeway in Star Trek Voyager. Maybe she did realize that herself and it was therefore she quit.
When I look at those video clips with Nicole Janeway, I find her rather woody and boring. The character lacks everything that Kathryn Janeway has in spirit, power and skills.
Having seen her in films, I can tell you that the clips really do not serve to show her talent. From all I've read she was truthfully having a very difficult time trying to adapt to the fast paced television filmmaking timetable and that painfully shows in her performance. I'm pretty sure if "Caretaker" were produced in the same manner as a theatrical film she would have have likely found her character and given a pretty great performance. As it was, it wasn't meant to be. This is why I think it's not fair to compare her performance with Mulgrew's because of the circumstances. Bujold was clearly not enjoying her time and it's a good thing Berman caught on and made the hard decision to recast after filming two days worth. Production is very expensive and it took a toll on the first season budget, but it was the right call.