The success rate if it's with a good doctor, staff, and PT is pretty high despite what mainstream media and redditors says. With US doctors like Paley and Assayag, you will barely hear any major issues, and if they did, they would try to get it corrected or minimally reduce risk asap. Assayag said it himself he has a 100% satisfaction rating, now of course we can be skeptical of that, but it also shows his confidence with his medical staff, and that we really never hear any sort of major issues from any of them.
The probable reason why it just gets a bad rep probably has to do with a lot of complaints from doctors in other places like Turkey, where we see a lot more horror stories. And since a lot of them are cheaper and more accessible, a lot more people would go there, but also the risk is higher, so you get more people who are more vocal about it and with social media just picking it up as just totally flat out dangerous. A good doctor would definitely monitor you properly and your x-rays, as well as advise you not to do something dangerous like overlengthen well above what's deemed safe that would risk mobility or cause other issues affecting not just bone but soft tissue.
If done well, you're looking at a good recovery at 100%. I say recovery as in just healed from damage to the bones and tissue, but mobility will still never be at your 100% nor is your athletic capability, due to a lot of other factors like biomechanics, soft tissue elasticity, etc, but at the very least it will be good enough close to it most likely especially with continued PT, resistance training, etc. We've seen people with great results and still have some good athletics and would also be weightlifting. But as we've stressed before, unless you're a professional or going professional, athletics is not something you should 100% worry about.