Depends on what price you buy PP at and what you are looking for.
You get a subpar idol raising game with about 2-3hrs worth of the typical Neptunia dialogue (with the blank inserted character that the fanbase seems to hate). On the gameplay side, you have 4 routes, and for your first run, it'll usually take you 2-4hrs. If you want a platinum trophy, and have a guide, it only takes 10-15hrs, in which you'll see all the dialogue the game has to offer.
If you want the dialogue, getting it for 10-15 is not bad. If you want a decent gameplay length/price, hope somehow you can get it for 5. If you want fun gameplay, don't get the game. If you want to complete your collection, does the price tag really matter all that much xD?