Reviewers love to rip "Voyager" to shreds, but the fact remains that it has plenty of fans all around the world. The abundance of fan art, fan-ficiton, Trekkies who attend and record "Voyager" panels at conventions, and twenty-something-year-olds who look back fondly on the show as an integral part of their childhood, is proof of that.
If one judges "Voyager" for what it is—an episodic sci-fi show, in the vein of "the Original Series" and "Next Generation"—it's a fantastic show. Most episodes are able to stand on their own, while also working into a longer, ongoing story. You can pick an episode from any season to watch, if you wish; but if you watch the whole thing in order, you can also appreciate how the characters evolve and the situation changes over time. Each season offers a balance of episode types, from "epic" ensemble-cast adventures, to single-character focused stories, to humorous episodes.
"Voyager's" characters are it's strongest point. Though a few characters were sadly neglected all too often (Chakotay, Kim, all of the recurring characters...), those that do get focus develop wonderfully. The cast in general is far more flawed and complex than the elite, best-of-the-best crew we got on "Next Generation."
The show's genuine flaws come in the form of rushed writing, and some wooden acting. Chakotay, Kim and Paris all fluctuate in their acting abilities, ranging from lively powerful performances, to sounding like they're possessed by Nicholas Cadge. (Though, in retrospect, it's entirely possible that the show's three main hotties weren't hired for their acting talent.) Some of the biggest plot-twists of the show also happen all to suddenly (including cast changes, and the events of the series finale).
Verdict: If you like "Star Trek" for the science-ficiton based plots, "Voyager" will no doubt feel repetitive and trite. But if you watch a show for the characters, I highly recommend it. If you're looking for a new arc-based show to kill entire weekends with, "Voyager's" probably not the right show; if you want a show where you can pull out a good or great episode to watch now and then, "Voyager" is a good choice.