More impressions:
I don't know if I mentioned this earlier, but there are NO speed modifiers in this game at all.
Hands and gimmicks can be turned off in ALL modes, not just Free.
One unfortunate thing about the Konami originals in this game is that about 5 or 6 of them sound eerily similar to each other. It's not too much of a deal killer, but it sort of reaks of Naoki being Naoki in terms of his music. (edit, just viewed the credits and yeah my suspicions were confirmed. I've venture to say 85% of them are Naoki Maeda songs)
If you're a huge fan of the original versions of Candy, Breakdown, and Love Shine, you're either gonna hate the English remixes or love them. Me, I like em. It's something different.
You don't have to full combo a song for a AA, however maybe it's just me but the requirements feel like they even more strict than DDR Supernova. This coupled with the default 1x scroll rate and getting an AA feels like an uphill battle on some songs.
Unless you can get a good dance pad from somewhere, or you go through Groove Circuit Mode on nothing but Beginner and Light for as long as you can, you are gonna find yourself doing what we call CCR, (controller controller revolution) With me playing on Heavy, I wouldn't DARE play the crowd challenges on foot with some of the songs that do come up.
I seem to do a little better with the system set at 4:3 aspect ratio, since for some reason in 16:9 the gray receptor arrows look a little funky (I got a feeling it has something to do with every other DDR on PS2 was 4:3). That's just me being me though, probably won't bother the majority of people.
Overall my opinion is this, if you're coming off of Mario Mix and is looking for a new challenge by all means buy it. If you bypassed Mario Mix and are thinking about buying your first DDR, get it. It has a bit more of a difficulty curve if you're new to the series as opposed to Mario Mix, but you won't find yourself having to learn new gameplay methods if you start playing at the arcade.
However, If you MUST have your bemani crossovers and hate the idea of playing to a songlist that half American covers (even though they're really high quality and have good to outstanding charts), get Supernova 2. If you need your speed mods and Oni courses get Supernova 2. If you want really hard boss songs, get both. If you don't know what I'm talking about here, completely disregard this paragraph and buy it.
I love this mix, it ain't perfect but the things it gets right it gets incredibly right. It gets my overall seal of approval.
note: if you do get it, depending on your TV you may or may not have to adjust the timing window. default is 0, I had to set mine on +8 to feel right.