Players should be able to progress in the game well enough without needing extra items. I was very impressed with the game, and given that it's free and a universal app, I would definitely recommend it.
It's hard to shake the feeling that there's a trap waiting around the corner to justify the free pricetag of Bullet Time HD (such as an impossible enemy/challenge), but it never comes, making this a worthwhile pick up for action gaming fans.
It suffers from repetitiveness and a lack of variety in its quests. But if you want a simple TPS that doesn't need a lot of thinking, you can give it a chance. And you can also end it without the needing a cent.