Yeah - it's "noticeable" from the first screen - the whole menu system has a new colour scheme. Outside of the cosmetic changes, everyone gets a new V-Trigger, there's a gallery section where you can see various SFV artwork and stuff, Team Battle mode returns from SFIV (although it can only be played locally it seems), there's a new challenge mode where you can pay ingame currency to attempt challenges that reward you with cosmetic items (costumes, colours) and there's your traditional Arcade Mode where you play through a series of matches against AI. Arcade mode has an interesting structure as well - you actually pick from several themed challenges based around older and current Street Fighter games, and when attempting the challenges you're using characters from those games (e.g. the SFIII challenge has you using Ibuki, Urien, etc.) One thing I missed in the pre-release news (but which came as a nice surprise) was the return of bonus stages. In older games you'd have the bonus challenges where you destroy a car, counterattack a beach ball or karate chop some roof slates or something. Here, I got to play the old barrel game from SFIV where barrels roll at you and you have to use the right attacks to break them. It's a nice inclusion.
For a free update, it's pretty generous, and I feel like the game would have been more well-received if it had launched with some of this stuff. I probably won't bother with season 3 of the DLC just yet (other future releases will be eating into my SFV time) but the Arcade Edition stuff is substantial enough to bring me back for a while.