Season 4 had no weak episodes and some extremely strong ones: like the season opener, the start of the main plot arc (Apocalypse, Nowish), and all the Angelus episodes. But Home packs more emotional punch than the rest of them, and is perfectly written and directed.
In "Home", Lilah shows the heroes around the Wolfram and Hart facilities, forcing them to decide whether to join the company, and Angel deals with Connor's madness once and for all. One thing that throws people off about "Home" is that it sets up season five with the tour of Wolfram and Hart, THEN resolves season 4. It seems like the opposite order to do things, but it's the only way that would have worked. If the Connor storyline been resolved halfway through the episode, then the tour of Wolfram and Hart would have been anticlimactic. Connor has been a problem for Angel all season, and it was only fitting that it would conclude with Angel finally fixing him.
And what a fix it is. Angel has to make a huge sacrifice to save his son. Although I don't like the Angel/Connor storyline of season 4 as much as the Buffy/Dawn one in Buffy season 5, this one is wrapped up perfectly. Dawn's character was trivialized in season 6 and 7, which was a shame because her original story was so good.