I disagree with you.
His cane and limp are gone because he now last his arm in Ionia, making a deal with Beatrice (who is still there you guys) to get a fancy new demonic arm and immense power. It basically revitalized him.
Birds: Have you seen videos with Swain? I've been playing him against a friend in custom on the PBE. His passive has birds, his W has Beatrice's eye, his ultimate he grows Raven wings as well as has Beatrice's head appear when he activates it. His recall has Beatrice fly around then go INSIDE his arm, so she's clearly there inside him. Additionally, as he walks around the map and uses abilities Ravens start to fly into terrain around him and it's absolutely awesome. Within like a screen radius of Swain there are always ravens, and I think more fly in to watch the carnage the more souls you have. He doesn't LITERALLY have a bird on his shoulder anymore, but he now has 3 abilities with birds or Beatrice's eye which, by the way, is up from two since it used to be his ult and bird yelling on the ground move.
Grizzled war veteran: Swain is still a grizzled war veteran and still was crippled in Ionia by Irelia. However, him being crippled didn't break him and led him to find a power that gave him the ability to see far more than he would've imagined. He has a quote for Irelia that basically says "you did me a service by cutting off my arm" and that's because he never would've found Beatrice otherwise. Just because he's not "oh whoa is me I'm a grizzled old man who's seen some shit" he's actively taking what he's seen, not letting it break him, and single handedly trying to steer his nation away from destruction. It's badass.
Original ability mechanics - He still has a mana refund, a root, an AOE long lasting lifesteal ultimate, as well as some new abilities. Swain used to be a point and click AOE champion and he's actually interesting now, it's not like Galio where they took a mage champ and turned them into a tank champ. He's still a drain mage and has more tools to do so.
Decent color scheme - I think this is your only valid point and it's only because Vladimir exists. He is extremely badass on his own but I wish they had kept his brown hair and had some other colors to his model. Other than maybe being samey to Vladimir, it's not half bad and demons as far as we know have their color palettes based on personality. Evelynn is a flirtatious pink and Tahm is a grimey green man who suckers people in, Beatrice is clearly extremely powerful and has no regard for human life. It fits, even if you don't like it or think it's close to Vladimir. Plus he still turns into a bird with the Tyrant skin for old times sake.
Sustain in laning phase: If you mean mana sustain, yeah he's easier to run out of mana with now. As far as health though? Sure his ult has a cooldown now and you can't just turn it on to get HP back, but his E can be used to get health as well as CC from a jungler gank. His ultimate now only helps him sustain now but pushes for kills with the second part of the ult damage.
Ebb and flow: Subjective. I personally think old Swain was pretty lackluster but now he can trade better, be more useful in teamfights, push to kill his lane opponent easier with CC, etc.
At the end of the day it just depends on who you ask, but lots of us here like new Swain. I feel bad you feel like you lost a champion, but in my opinion this is one of the best reworks Riot has done surpassed only by Evelynn and maybe Warwick. If you want to see an absolutely horrible rework look at Galio, who changed classes as well as personality immensely, or Trundle who literally lost everything interesting about him, moved across the continent, became an ice troll, and lost his sarcasm and wit.
fans when xerath got his relaunch despite the old xeraths kit being complete trash compared to his new one. people for some reason wanted his useless old w back.
