Is there any heating issue with OnePlus X ?

Personally, I haven't used it but going through forums and other reputed sites reviews. I think it has some heating issue while playing high-end graphics games.

Battery Drain is also parallel with the heating issue.

The users have reported heating issue with the OnePlus X. It has been observed to be heating up while playing games for a prolonged period of time. Though, it is common for Android devices to heat up while gaming, the case with OnePlus X seems to have something to do with the Snapdragon processor.
The device is found to heat up at the place where the CPU is positioned and also around the battery.
However, the latest software update to OxygenOS 2.1.2 A has been reported to have addressed this problem. Many users have reported that the update has resolved the heating issue.

If you check One plus forums then you'll notice that X model has issues with heating even for normal video playing or image capture. Though battery drain and heating is common if the person is playing the game.

e.g problems as explained in here: https://forums.oneplus.net/threads/one-plus-x-battery-drain-and-heating-while-gaming.403880/

I even understand the heating due to the browser open with 3G turned on. However if the heating occurs during video play or while capturing images, then it seems like an issue. Though the battery drain and heat due to network load is software issue. It could be possible that it'll get patched. However, heating due to the image capture and video play may not be worth ignoring. If this occurs due to software then expect this issue to be patched soon.