I didn't watch much Enterprise when it was on, unfortunately. Scheduling conflicts prevented me from fully enjoying the series, even though I did manage to catch the occasional episode. It's a great benefit to people like me, then, that the entire run is now on DVD.
The full season DVD set is especially useful for this third season, because the entire season is essentially one extended episode. The Xindi Saga.
It's interesting to watch as Archer and the crew (and the fledgling Starfleet, for that matter) respond to a terrorist attack on the planet Earth. All of the emotions that we felt after 9/11 are present in this season — as are the decisions that we've had to make (for good or ill). We see the conflict among the Xindi, and then we watch the various factions in Iraq battle for control. The parallels are interesting to watch, and are very much in tune with the tone set by Roddenberry in the original Star Trek.
Equally interesting are the scenes involving the Xindi council. We see a people who are not (all) warlike and violent, but who are intent on saving their homeworld from destruction by the human "threat" 400 years in the future. Bad guys who aren't (all) quite so bad is part of the Star Trek experience — even Klingons are now seen as a race governed by a sense of honor that humans cannot quite equal.
In the middle of this political commentary, a little social commentary is thrown in for good measure. In "Similitude," Tripp is seriously injured. Flox creates a clone, to attempt to help save Tripp's life. But the clone has other ideas about life, and whose should be saved. The episode gives a whole new perspective on the issue of cloning.
Season three of Enterprise shows a lot of the promise that the series had. I grew tired quickly of the "Enterprise as backstory" idea that seems to plague much of the series, and I enjoyed seeing an alien race that we don't ever see again in any Star Trek incarnation. Enterprise was at its strongest when it was allowed to function as its own series, rather than being so dependant on the rest of the Star Trek franchise.