I am giving this a 7/10 because if you ignore the ending which misses the target by a parsec, this could have been a really great episode. And if you make up your own ending in your head, it works.
The idea is great. A proto-universe that's expanding, threatening to devour our own. Now, there's no explanation where it came from, and the fact it just happened to stumble upon the runabout does challenge our suspension of disbelief, but as a basis for Star Trek kind of philosophical questions, it is as good as it gets: How can you decide the destruction of an entire universe? The doubts for the crew begin when they discover life in it, but that, I think, isn't even necessary. The fate of a universe in your hands - this is as heavy a responsibility as you can imagine. There are two directions it could go from there: either let Commander Sisko become death, destroyer of worlds, or find a treknobabbling way to return it back where it came from - personally, I would find the first much better dramatically, not the least because as I said, we are never told where it came from. Somehow, neither option is actually chosen. Instead, we are left with a "yay, we returned it to the other side of the wormhole", as if that is a solution. They could have said that the analysis showed that it is not going to expand beyond a certain (small) size, so leaving it in the middle of nowhere would at least make some minimum sense, but they didn't even do that.
So all in all, this episode asks a profound question and then not only refuses to answer it, but reduces it to triviality without even pondering on it as much as it should. But perhaps simply asking the question is good enough - and even though I had watched the episode years before this time, I could distinctly remember Odo's retort "I don't step on ants, Major". A wasted opportunity for something really good, but even woefully wasted opportunities are usually still better than mediocrities.
The idea is great. A proto-universe that's expanding, threatening to devour our own. Now, there's no explanation where it came from, and the fact it just happened to stumble upon the runabout does challenge our suspension of disbelief, but as a basis for Star Trek kind of philosophical questions, it is as good as it gets: How can you decide the destruction of an entire universe? The doubts for the crew begin when they discover life in it, but that, I think, isn't even necessary. The fate of a universe in your hands - this is as heavy a responsibility as you can imagine. There are two directions it could go from there: either let Commander Sisko become death, destroyer of worlds, or find a treknobabbling way to return it back where it came from - personally, I would find the first much better dramatically, not the least because as I said, we are never told where it came from. Somehow, neither option is actually chosen. Instead, we are left with a "yay, we returned it to the other side of the wormhole", as if that is a solution. They could have said that the analysis showed that it is not going to expand beyond a certain (small) size, so leaving it in the middle of nowhere would at least make some minimum sense, but they didn't even do that.
So all in all, this episode asks a profound question and then not only refuses to answer it, but reduces it to triviality without even pondering on it as much as it should. But perhaps simply asking the question is good enough - and even though I had watched the episode years before this time, I could distinctly remember Odo's retort "I don't step on ants, Major". A wasted opportunity for something really good, but even woefully wasted opportunities are usually still better than mediocrities.