Overall I wasn't too impressed. It was better than Season 3, no denying that, but it lacked something that Seasons 1 and 2 had that made them great.
There were some nice moments. Jack regressing to when Sydney was a kid was very sweet, and the flashbacks with Sloane and his baby was touching. Nadia and Weiss are my Alias OTP. Sooooo cute. Definite lack of Sark overall I would say
The last 2 episodes were silly. Reminded me of a cross between the Buffy Season 5 finale and a Resident Evil movie. Although when the car hit them right at the end I nearly fell out of my chair. It's almost worth watching Season 5 to see how that all plays out. I want to know what Vaughn's big secret is.
Oh, and Sydney's mother wasn't dead. Should have seen that coming