I am surprised that this is even contentious. Why wouldn’t you want a new option?
One of the things that bothered me about SF4 is the duplication in functionality in the Supers/Ultras. For most of the characters (with the exception of Dhalsim and maybe a few others) the supers and ultras are functionally the same (Ryu: two types of fireballs, Zangief: two types of 720s, etc.) From a game design point of view, they aren’t giving you choice, just a second shot at a super when you are below a certain health percentage. That seems like it detracts from the potential strategy of the game. You don’t play a Ryu with a super differently from one with an Ultra (which both suck by the way since he just tags them on to any low risk moves that happen to connect and get you in the air.)
So for me, I played about two matches with Ultra I, then said “hey, I’ve got a Super, I can often get two in a round, why keep another 720 throw around?”
In the past 10 or so hours (not much? I’m at around 1800bp in Tokyo) I’ve been using Ultra II and it is great. I only play network ranked matches so double blind selection, which means I can’t pick based on characters. I still find the Ultra II very useful. I don’t remember whiffing it. It took a while for me to get the motion down so that I don’t pop out an EX condor spire, but other than that, it has been great.
If you can bait someone into jumping - and the range is pretty good, Ryu jumps from 3/4 of the screen away after you hop a fireball, the U2 nails him - you can use it. You can use it to escape crossups (well, sometimes.) I’ve done random U2 Ultra, landed right in front of someone and done a super more times that I can remember (well, about 4. Still, wtf? That shouldn’t ever happen.)
Mostly though, once you have it, people have to think a bit more about jumping. It opens up more options. I like the Super just fine, and if I don’t have the super I can still do a fierce SPD. I’m not sure that fierce Tomahawk Buster is a replacement for U2 though.
Also, it just looks super cool.