I’ve only been living here in TC for a month or two, so take my comments with a grain of salt, but here goes. I also can’t really compare to KS.
Public transportation is imo still pretty awful. I can reliably youbike faster than taking the bus, and often the bus will arrive early and keep going or arrive way late. I’ve stopped taking it because of this… Just too unreliable, and a PT network hardly exists if it’s an unreliable network. There is a MRT line, but I find it rather limiting… It’s good from getting from Gaotie to the city, but for me it doesn’t really grant you a ton of great options of places to go into itself. It gets you near a lot of places you might want to go, but still far enough away that it’s just not that convenient unless you live right up alongside it, which you probably won’t given that it’s built along the mid-outskirt of the city.
For example, I’m in North District around Yizhong. For me, Yizhong night market area is great for food, so I seldom feel the need to go elsewhere. That said, the bars here are generally lacking or entirely not present. So i sometimes want to go around 草悟道 (Calligraphy Greenway). But I’m drinking, so I can’t ride bike or gogoro, and I’m too far away to walk back. The MRT is way far away, so it doesn’t get you access to that, and the bus after like 11 will takes around the same amount of time as to walk there. Ok, is what it is. Feng Chia is the same. It’s just not the most accessible PT for practical purposes. But hey, it works mostly, when the buses aren’t being ducky and unreliable. If you’ve lived in an European country, it will drive you mad though.
All that said, youbiking here isn’t bad. I can’t really compare it to other cities in TW, I will say the constant traffic lights can be a frustration and are part n parcel with the generally poor urban development of the city. That said, if you’re willing to brave the traffic – it’s not Taipei, there aren’t really accessible bikeways (with a few exceptions, such as the one I love very much running from North district to 草悟道) – the city really ain’t that spread out. I’m a decent biker, but not amazing or anything, and i can pretty reliably get around with it. Although it does scare the shit out of me still sometimes. The poor urban development means there are some awful intersections.
That all sounds pretty negative, but I’m just pretty critically attuned to public transportation issues as it’s a longtime interest of mine. It’s not exceptionally easy to get around Taichung efficiently by transit, but ultimately you can get around.
Otherwise, the vibe here is pretty chill. Much like anywhere else in Taiwan (I assume) the people are friendly but not outgoing if that makes sense – they rarely randomly start a conversation with you. Take that as a plus or minus as you will. But I find the temperatures pretty nice because it’s generally moderated by a nice breeze, pollution generally not too bad in the city. Costs here to eat and live are very reasonable. And as other posters have mentioned, it’s developing at lightspeed. New construction nobody can afford all over the place! 
As far as parks and such go, I’d say it depends where you are in the city. The newer districts parks are pretty nice to hang out around and are generally vibey. The civic park in particular is always insanely busy. the older districts are hit or miss. But generally there’s always at least one decent park around any district, and a handful of smaller ones. The presence of sidewalks is, much like the parks, contingent on the district, with the newer more moneyed districts having more of them. Surprise! Shopping wise, there’s all kinds of stuff and department stores and I’m fairly confident most people will be more than well enough off with what is available.