I'm not a software expert and I do not know much about codings and the working mechanisms of software so consider my thoughts as that of a layman.
I'm still relatively new on steemit but I think I understand the reason behind the recent upgrade and i find it's course justifiable. I know about the spamming issue and the content control that many people complain about and I believe that's what Steem.inc tried to stop with this upgrade.
Just like the bandwidth system before the upgrade, everyone has a space on the blockchain and this space is determined by how much steem power a user holds, higher Steem power equates higher bandwidth - now Resource Credit. With my amateur knowledge, the best way I could explain this is transactions are now paid for by Resource credits which are bought with Steem power, only that you only buy once and it recharges once it gets low instead of constantly re-buying.
With Resource credits transactions are more expensive than they were on bandwidths and the aim is that spamming accounts will eventually desist from the habit or risk using up their bandwidth which would recharge in five days. If you have noticed, majority of the bots that leaves hundreds of comments and valueless upvotes everywhere are low steem power accounts.
Was the HardFork a Success
I think it's too early to make a concrete answer. But if you are referring to a successful transition from bandwidth and voting power to resource credits and voting Mana then Yes! Yes it was successful, after the first few days of blackout things appear to be stabilized once again.
It it's aim was achieved, I can't categorically say for now, I have noticed a decrease in spam comments but that isn't enough to call it a success. I haven't been able to calculate the cost of transactions on the blockchain but I don't think they are as expensive as we initially thought them to be, I've observed small sp accounts like mine going about their routine activities without significant drop in Resource credit and I fear the charges are not high enough to encourage users to either stop spamming or get Steem power.
But I guess we will just have to wait it out.