I spend a lot of time reading reviews and I feel it's finally time for me to try one.
Ultimatum #3.  I have been a huge fan of the Ultimate Universe almost from the beginning.  I was excited by the idea of Ultimatum and have thoroughly enjoyed the first three issues, as well as the tie-ins.  I also just read Ultimate X-Men #100 was glad to see it end on such a high note.
Anyway, Ultimatum has been everything that event books always claim to be.  Things happen!!  Characters die!!  And nothing will be the same when it’s all said and done!  Characters are dying, and I refuse to believe it's without reason.  A tidal wave destroyed New York City.  Were all the heroes supposed to live?  Millions of citizens die, but the superhero community survives without a casualty? Characters are reacting desperately in the face of horrible events.  Hank Pym bites off Blob’s head!  Gross?  Without a doubt.  But he sees the woman he loves being eaten.  Of course he would react suddenly and violently.  Later in the book he kills himself.  Hank would kill himself; suicide is a selfish act carried out by people who only think of themselves.  That's Hank, at least Ultimate Hank.  Loeb's recieved a lot of flak for not understanding these characters.  While he my lack subtlety, he knows these characters.
Thor, for example.  I didn't like Thor sacrificing himself for Valkyrie but I feel it's totally in character and won't turn me off from the series or what comes next.
Things continue to build in this series and I am enjoying ever turn of the page.  There truly is a feeling of not knowing what might happen next.  I for one, and apparently one of the few, can't wait for the next two issues.