ZSS was pretty underrated to begin with, and was one of the few characters majorly buffed in 3.5 (dat grab tho)
woah woah woah, she was not majorly buffed. She had her bread and butter from 3.02 flat out removed. Both of her best neutral tools are no longer even neutral tools, and her dsmash went from being really good to being exclusively for tech chase and edgeguard, and she took a huge recovery nerf (still relatively good recovery, but still). Not to mention, none of her previous weaknesses were fixed. Also, that amazing new grab? It kinda sucks. Her throws are literally the worst in the game. Hold the right direction (same direction for every throw) and she gets zero follow ups save for some very specific %s against very specific characters. At low%s or against fast fallers, her dthrow is a tech chase, but not a particularly good one since the throws are so laggy. Not to mention, once you get past low%s, you can DI in a way that denies a follow up and a tech chase on many characters, and that DI denies follow up on her other throws too.
I understand the rest of the cast was nerfed too, but she was not substantially buffed. It seems people either look only at her strengths or only at her flaws. She has some incredibly strong strengths, but also some incredibly impact flaws. You all seem familiar with her strengths, and they are definitely pretty strong, but here are her flaws detailed.
1. Really bad throws. Name a character and that character has better throws. Almost every character in the game has some sort of guaranteed follow-ups on throws, and every character that doesn't is trash (not really sure there are any, come to think of it). Her up throw is neither good for position, nor can it kill or combo without dump di. Her forward and backthrow have no follow ups regardless of DI, send at a bad angle so you can't get tech chase, and don't send offstage very far.
2. Very weak kill options. She has almost no combos into kill moves, and the ones she does can almost always be DI'd or SDI'd (fair). And no, dsmash doesn't count as a kill combo because hitting a raw frame 20 smash attack isn't exactly consistent. She can get downsmash off tech chase, but that's not the most reliable. Also, she struggles to get tech chases at higher %s unless against fast fallers. Pretty much her only way to do that is up-b on an aerial target, but that rarely leads to a legit tech chase. You have spaced bair, and that's great, but it's telagraphed because it's the only thing you can do while facing away. So, basically, you either have to get a hard read, land spaced bair, or gimp for kills. Very similar to marth, but marth has better kill combos and cannot kill absurdly early with one good smash. Granted, marth also doesn't have a kill option as good as bair.
3. Trash smash attacks. Her smashes, with the slight exception of downsmash, are basically useless. Her upsmash is usable now, but it's still pretty mediocre. Not to mention, missing up or fsmash leaves you vunerable for so long your opponent can do anything to you. Fsmash has around 45 frames of lag, and start up of 20, for over a second long move.
4. Struggles to combo fast fallers. She has tech chases, but that's not how you excel against fast fallers. Most fast fallers primary weakness is being zero to deathed easily, but ZSS has the opposite problem. She doesn't have moves that reliably knock straight up for combos save for uptilt, but uptilt is fairly laggy and can be CC'd and SDI'd out of. This is particularly problematic since most of top tier is fast fallers (spacies, roy, falcon etc.)
5. Very weak to CC overall. Not much to say here, but most of her non dsmash or spaced bair moves lose to CC pretty badly. Even side-b gets wrecked by CC on sweetspot.
6. Really bad spacy matchups. Most characters have a bad spacy matchup, but ZSS has it particularly bad. It's like all the problems falcon has against spacies x5. Her only saving grace is that she is decent at gimping them. Normally specific matchups.
7. Low overall damage values. Not much to say here, just that her damage values are below average. She makes up for it by racking damage well with combos, but still worth keeping in mind.
8. High aerial lag. Not a big deal, but if you throw out an aerial, you can almost never use another one before hitting the ground. (note: not talking about landing lag)
Now, as an honorable mention, here's why she's not falcon.
1. No knee. This is the number 1 thing that makes falcon better. Falcon can kill you at 60 at any time if you aren't careful, and can combo into it even off of throws. Knee and combos into knee is a threat to kill at basically any % for most characters.
2. Longer landing lag on aerials, particularly combo starter aerials. This patch, her only combo starter aerial is upair, with 9 landing lag where falcon has 7 on nair and upair.
3. Lower shff speed. This comined with 2 means falcon has faster combos.
4. less safe neutral game
5. No falcon jab
6. Slower with less air speed.
ZSS does have her fair share of advantages over falcon as well, but this post is just listing weaknesses. Since it would be easy to read this post and assume I think ZSS is bad, please don't assume that. She is a good character, but that's because her strengths outweigh her weaknesses. Most top tier characters don't have that many large weaknesses, if any weaknesses at all.
Overall, she's top 20 at the least, top 15 at the most. I'd put characters like marth, lucas, samus etc. over her. If you want me to list her strengths as well, I will.
What is this DI that doesn't let you get a tech chase? AFAIK, DI'ing away means a tech chase, and DI'ing in gives ZSS followups, so you always want to DI away.
It's kinda like falcon dthrow, but with much more lag and a lower trajectory. If you DI up and away at mid%s on floaty/semifloaty characters or high mid%s on semi fast fallers, you don't get a tech chase, especially if they have a fast aerial so they don't HAVE to jump out.
(P.S. Yes, this did take me over an hour to write, but granted, I played league games in between writing.)