It's not. High Voltage has been fired and replace by another company but the game hasn't been patched since. It will be fixed eventually but there's no words on when yet.

Don't get why Devs can't delay the PC version and do it themselves instead of outsourcing its just lazy lol

If its nice and cheap it wouldn't be a horrible investment, but if you already have it for PS4 or Bone its not worth it. I bought MK9 for PC during a Steam sale last year for 4.99 just to "have it forever". I'd wait on MKX for that as well.

where did you get the news high voltage software got fired?
if you are talking about that Q-Loc rumor,nothing's been officially announced yet.
from what I've heard and seen,MKX is nowadays a lot more stable on PC.(although not perfect,mind you.)

just saw a £15 offer including the kombat pack, I don't know whether to go for it or not

From what I've heard from everyone is that performance has been greatly improved. (this is from the previous patch,not this one)
Honestly,it doesn't sound like a bad offer. if you have an up-to-date pc that can run modern games without problem,I'm guessing it should run fine.
they did mention in the latest patch that they fixed several crashes(some display driver crashes,a training mode replay crash as well as an odd crash where the game would minimize and then just freeze) so,if this latest patch is to be believed,it certainly seems to be more stable than before. (the performance from what i've seen in PC predator gameplay videos is good)
one thing to note: balance patches(along with their bonus content) tend to arrive later on PC.
If you don't mind that,then go for it.

It's a high end PC should play it at 60fps maxed at 1080p

then go for it. seems like a really sweet offer,and as I stated before,the PC port is far more stable than it was at launch(again,based on what I've heard and seen) but the balance patches do take longer to get released compared to the console patches.

I have it for my high-end asus and its pretty dam good and it is fully patched with the latest updates.

I heard a huge patch came out the other day that fixed a load of problems. PC version should be stable now.

yeah,that's the predator patch. it further optimized the performance(it was already optimized before this,that's when it finally had a stable FPS),removed the frame skips,and fixed several crashes(including some rather odd ones,like the training replays I mentioned before)