He's being picked a lot in the recent tournament. Not over the top a lot like "roit nurf noaw" but enough that you should respect him as a champ and what he brings to the table.
I get the feeling that most of the people who whine about j4's ult don't play the champ or maybe played him once and don't understand how to use his abilities properly.
I guess his shield could use a bit more, but I kind of like it as the no point wonder as it is. If they made his shield useful they'd probably have to take things away from other parts of his kit which is no fun for the jarman.
Though as for the OP I doubt he'll really be fotm. For a 2 button champ he's kind of hard to use. He also doesn't do well in blind pick games where all of a sudden you're matched against a nidalee, a vayne, an elise, kass, shaco, etc. FOTM champs tend to be spammed becuase they are good in a lot of situations. He'll gain some popularity no doubt but never to the point where you see him every single game. He should be almost exclusive to draft pick where you can see what you're up against, imo anyway.