Dragon Souls design and bosses have been mocked for weeks now, with every single way possible i think. I was not happy with the amount of bosses either. But there is one thing i love about dragon soul: Blizzard designers have clearly thought about dps classes this time.
I mean dps for the sake of maxing your numbers. Encounters that let and force you to do maximum dps. There are only a few "be aware of something"-mechancis and a lot of "dmg increased for x%" mechanics. It might make the raid easier mechanic wise, but it challenges you dps wise (some people face challenge in normal ultraxion, most in heroic bosses just because of low dps). The reason I like this is that it challenges you to know your character, and to research and do everything to max out your dps. Bad players of their class can learn mechanics in 5 tries, but not improve 10k in dps.
Firelands was shit if you watch it with a similar POV. Bethilac was dumb with all those small adds to dps down there, alysrazor only had 1 caster dpsing him properly while others killed adds, ryolith and his damned legs D:, majordomo who seemed to have increased parry chance during cooldown phases (:P) and had to be dps'd in front. I loved raggy fight but it was not a dps race in normal either. Most hc modes could be cleared without great dps because of the lack of tight enrages. Firelands mostly did not encourage you to get better as dps.
Ultraxion is a dps dummy, but in a good way. His enrage can be tuned tighter because of the lack of other mechanics. I like a boss that tests you as a player of your class. I've never seen as much topics about guilds wiping on a boss simply because they can't beat the enrage, as i am now. Even in normal mode. I feel better for being a good player of my class and getting result with that instead of "switch between 4 pointless adds" or "move here and wait 20 secs" mechanics that everyone can learn fast.
Zon ozz is a dps dummy. Apart of the bouncing, he was very few mechanics on normal, but he has a mechanic that makes him take more damage. That kind of mechanic makes dps simply more fun for me. This kind of fight beats bethilac and rhyolith (my most hated bosses in FL) 100-0. A boss that seems to have been created only with high dps numbers in mind. I don't see what's wrong with that.
TL; DR This is only my POV but DS is a raid designed with dps players in mind. It's about getting and having to do dps more than anything else.