It's hard to find any reason not to recommend Crisis Core to RPG fans in general and FF VII fans in particular. The lack of an overworld map and button-mashing combat may be off-putting for some, but these are really only minor blemishes in an otherwise flawless package. Just like saying you wouldn't date Cindy Crawford because of her mole, refusing to play Crisis Core based on these small issues amounts to simply being overly nitpicky.
More than just recommending the game, Crisis Core is a genuinely great reason to buy a PSP. If you've been on the fence about grabbing Sony's handheld, then go ahead and pick it up and make this your first software purchase. You'll be truly glad that you did.