To me, as a Namor fan, any new book that he is consistently a part of (this is why I don't really count New Avengers), is a must to read and support.
So, yes, even if the art was crap, I'd probably still read it. Well, I'd read Invaders, anyway, because they're my favorite superhero team, so I am slightly biased.
But, yes, the art improved and the writing just got SUPER AWESOME.