I actually legitimately honestly think marth is not as good as people think due to lack of top level options compared to the other characters with better up close moves. I've never really found marths difficult to fight either, for like 6 years now. This is including Ken/Azen's prime. I've beaten both Ken and Azen in sets with Fox and Marth both, in all 4 combinations possible, this was before I picked up a good sheik also or got to try my other characters out. In fact I've 4 stocked Azen in tourney in marth dittos in his prime (end of 06).
Despite this, I still believe my 07 marth could **** a lot of things back when I practiced and didn't play brawl. I think brawl messed me up. Not a lot. Just a little, but enough that i lose a lot of close games that i otherwise probably wouldn't due to small errors that add up that wouldn't happen in old days before brawl. It probably made me lose tons of sets I would have otherwise won. Anyway, that's my honest opinion on marth, overrated, but still extremely good. In 07, I used to be able to jv 5 stock a LOT of players, even good players, with marth, in both friendlies and tournaments. I did it like once or twice every tournament on average, and i went to a lot of tournaments.
I also was a lot better with marth overall when i only used him and didn't play other characters. I stopped cuz:
1) got bored (I get really bored of using only 1 char in this game that's why I use like 7, but I never really focus on just 1).
2) brawl
3) I believe he's limited in his options (or good options, and overall risk/reward scenarios in many important high-level situations. Sheik for example, has a fast nair OOS, a faster roll, faster dodge, and better shield. That's 4 superior shield-based things. It's honestly very significant vs fox and especially falco).
I do believe if this game was ONLY Final Destination, and no other stage, then Marth would be the best character in the game, losing head to head vs sheik, but going 55 45 or better with all the other top tiers and high tiers. Marth struggles a lot with KOing when fox/falco aim for the top platform, and chain grabs are also really bad in those situations with a top platform.
Unfortunately he sucks on counterpick stages, and really sucks in teams. His main use is on FD. It's not even that marth is bad either, it's just he's not in the same class, option wise, as the 4 above him. His frames aren't good enough once you get inside him. Like sure, he has options to get away, but I'm talking risk/reward ratios. It's overall very bad in those situations, and they are forced upon him a lot. Sheik does not suffer this weakness. Marth can't really do anything about shine-grab. Actually most characters, except Fox, can't do much about it. Even if I rolled away, Falco's not at a disadvantage, it's just an evened out situaton. If falco shine-grabs, he has like a +2, and +1 when stale, advantage for grabbing even before I can frame-perfect grab. It's pretty dumb. If falco hits me with shine, and misses the grab part of the shine-grab, I am still in enough hitstun to be comboed off of it with falco's double jump Uair after the grab-lag ends. I think Fox's shine-grab is not as good because if I get shined by Fox and fox's grab misses, unless he is REALLY close and ALSO sliding towards me (meaning it can't be done after a Nair for example), i just get shined away for 4 damage and it's not a big deal.