First of all I have to admit that it's an ambitious and different approach to ending a series with a dramatic finale involving the ultimate nemesis borg queen. I love to see Barclay again and the fighing scenes are impressive. It would definitely be one of the best episodes of star trek voyager if there wasn't this extremely illogical and untypical error the whole episode is build upon: How for heaven's sake could Admiral Janeway want to change history? Didn't she learn ANYTHING about what could happen then? Didn't she always fight people who want to change history in their favor, like for example the Krenim Annorax from the "Year of Hell" - Episode?
I'm worried about that and I don't find an explanation. You could say she's old and out of her mind because of the loss of Chakotay, but why would the others like Barclay and Kim help her?!
With that alteration of history the Borg get advanced technology way before they should see it, the Voyager is being kept from helping who knows how many people (on their way home to the Alpha Quadrant) and the timeline is being changed significantly. Who knows what other effects could emerge from that?
Star Trek always wanted to give a good example of how to behave and what is good or bad, but this series finale is a moral and ethical disaster. It implies that it surely is ok to alter history if you change it for a better future for you and your friends, a fact also this series has fought against several times.
And it's not that in the future of Admiral Janeway everything's destroyed and the Borg have taken over, you might sympathise with her approach then - it's just that "some people" died. I just can't understand that storywriting and I'm very disappointed from such an ending to a very good series.