Michaiah doesn't completely ruin FE10, I just feel like FE9 had the better plot, personally. I dunno, maybe that's just me being a sucker for simple plots that are secretly more complex than they seem.
I do love FE10's gameplay, but I've already stated that XD
As I've stated, I like FE9 the best, probably because like the GBA Fire Emblem games, the plots were complex... but simple at the same time. I believe FE10 just has some part where you're like 'wait... what'. Honestly, I really think it's because of Michiah... gaaahh... she is only useful for healing and thai, I swear, lol. That... and I tend to like more Lords better when they can DOUBLE.
Rant over Michiah aside, FE10 is still a good game. I really love the gameplay. If they had FE10's gameplay in FE9... I'd never stop playing FE9, lol.