Let's start off with my character analysis.
Character wise, the game seemed pretty bare at first, requiring the player to unlock about half, maybe more, of the roster, and 3 of them as secrets. It's been a while since I played Melee, but I'm confident that there were fewer to be unlocked, proportionally of course, given the roster size. I had already been following character announcements and knew Roy wasn't going to be in the game, much to my dismay, but I had my hopes up for the reintroduction of Marth, and the addition of Ike. Overall, the roster became very well developed and I enjoyed it a lot, even while I was missing my beloved Roy.
Graphics and Sound wise, it wasn't anything amazing. The graphics definitely improved, but not a whole heck of a lot. Overall they did a nice job upgrading the look and feel of the game, including he Melee levels. The sound was crisper which was really nice, and the soundtrack was amazing. There were so many songs.
Level wise, I was quite impressed. I enjoyed the inclusion of new levels and ideas. Frigate Orpheon was interesting with the flipping while Animal Crossing was nice with the date/time inclusion into the level and the Wario Ware level put a unique spin on things (imo) by giving players power ups for succeeding at beating the little mini games.
The adventure mode was interesting on the first run through, though the countless baseless wave type battles did get tedious at a certain point. I will admit that I did become frustrated with some of the enemies at more than one point because I thought some were quite over powered.
Overall though, I was simply happy to finally have the game I had been following progress on for almost a full year.