For gaming, no it won't be worth it. The only benefits you'd get would be multicore performance, when doing video editing/rendering or compressing video via handbrake. Wait for Ryzen's budget cpu line to be released and build a whole new system.
As a new upgrader from 4300 to 8300 go for it ! but for the money....was a bad idea for me i guess
Thanks, so I'm good to stick with FX 4300 till Ryzen goes out and till I can afford a new motherboard with AM4 socket + DDR4 RAM.
Depends on the game. If you're playing Battlefield, then you will see a nice FPS increase since BF makes good use of the extra cores. However, I certainly would not buy an FX8300 until after Ryzen is released. Prices will hit the pavement.