Just to put in perspective how big of an impact Hidden Arsenal 7 will have on the game for the rest of... well, ever, check out the following two lists. The first is of decks that will become better or are new to the game entirely as a result of this set; the second is a list of cards that will likely change the game across a wide spectrum of different decks and strategies.
4. Gishki Zielgigas OTK
5. Evigishki Levianima OTK (http://yugioh.tcgplayer.com/db/article.asp?ID=2705)
7. Gadgets (and Machine decks in general)
1. Lavalval Chain
2. Daigusto Emeral
3. Evilswarm Ouroboros
4. Constellar Ptolemy M7
5. Tin Goldfish
Rest assured: Even though LTGY is a big deal of a set, this one definitely shouldn't be underestimated either. Thanks for reading!