Mechanically, there's a host of changes from SF4. There's been a shift in design philosophy, away from the more complex combos and 1 frame links of previous games, to having more leniency in your moves and combos, allowing you to focus more on spacing and footsies. Your execution in games still matters, of course, and you'll want to put time into training mode, but you should be able to spend less time on difficult execution training and more time developing strategies for conquering your opponents.
