I have to chip in and add my yes, yes, and thrice yes!
It's a bit tongue in cheek, don't watch it if you want plausible storylines! It's a FUN show.
Seasons one and two are of course the best.
Season three isn't bad.
Season four is horrible, I hate it... eugh.
Season five I loved again, it brought back the absurd fun of Alias.
Watch Alias! I also found it has a really high rewatch value, having seen most of it about four times. And strangely I feel I could watch it again now. Not sure what it is about that show...
Oh, and just shout at the dump-as-a-brick Vaughn when you watch it. God I hate him.