Wow! Earth blowing up, the bridge of the Enterprise being destroyed (with the senior staff still in it), and the imminent destruction of the entire human race.
They pulled no punches with this episode, and you really start to realize just what is at stake should Enterprise and crew fail their mission. If this doesn't get you into the Xindi storyline not much else will.
Fabulous acting, incredibly well written dialog, and the special effects and space combat sequences are out of this world (lame pun I know).
Not my favorite episode of Enterprise, nor do I consider it the best of the season but... this is what Enterprise and Star Trek is all about.