is Haswell iGPU good?

It all depend's in what games you want to play, and what you consider as playable. On that i3 (Intel HD Graphics 4000 - 20ExecutionUnits) you will be able to play many games on lower settings. For sure games like: Drive San Francisco, Torchlight 2, Diablo3, Skyrim (low). But newer games also need better gpu, so if you prefer Intel over AMD and you plan someday to put i5 on your mobo its even better to buy older used midrange graphic card (it can be even used Radeon 6670 for 50$). For example Alien vs Predator 2010, Battlefield 3 are more gpu intensive so dedicated graphic is a must for them.
 


if i buy a 6670 will it be good?

 


Wait ! Dont buy hd 6670 . For now Intel HD Graphics 4400 will be enough Save some extra money and get HD 7790 , R9 270 , GTX 660 ..
 
As I said, only used 6670 with gddr5, should be arround <50$ (price from Poland) new one aren't cost effective, you ma buy such used and sell later with little difference and get much better gaming experience than with intel HD. Or get more $$ and buy something from newer Radeon 7xxx series or similar ;]
 
The HD 4400 GPU is actually fairly decent.. what games were you thinking of playing? Have a look on YT for the chip and there's plenty of videos around showing off it's capabilities so you can see what sort of performance to expect.
 


far cry 3 , portal , half life 2 and skyrim