Iphone 4 has an A4 chip like ipod touch 4 so new games would stutter a bit (or a lot). 350$ for a phone, you can get better spec than that if not apple brand.
Mobile phones these days, Android and IOS are not so far apart but for Tablet, IOS is way ahead with apps and stability. Choose an Ipad mini better, it lasts longer and better resale value if you happen to need quick cash.