Welcome to the board. There will always be people who are unhappy with the outcome of a surgery. In spine surgery in particular, there are no guarantees as to how it will turn out. I would suggest you do not enter into this without very careful consideration. Do as much research as you can.
You can type XLIF into the search box and you will see many earlier posts pertaining to various people's experiences with this particular surgery.
I would assume that you would be in much better hanRAB with a surgeon who has done this procedure hundreRAB of times. Perhaps this was not the case with other posters who are reporting less than successful outcomes.
Don't be wooed by the "walking the same day" claim. ALL spine fusion patients are expected to get up and walk the same day. Just because you can do it doesn't indicate the amount of pain it may cause to accomplish it!
Also I would just add that a doctor's or the medical profession's definition of "success" is often VERY different from that of the patient. My first fusion was a success to my doctor. He proposed a PLIF for L4-5. He accomplished the surgery without incident. My recovery went smoothly and I healed properly. On paper my surgery was considered "a success." However, I ended up with the same pain and inability to stand or walk that I was dealing with prior to surgery. The fusion did not resolve my issues.
If you hang around forums such as this long enough or talk to many people who have had spine surgery there is a common experience for many concerning the word "success." Many patients are left with more pain than they expected. They then learn that six months out, as far as their surgeon is concerned, he did his job, (and did it well, as they are quick to point out!). At this point, many surgeons are finished with the patient. If he or she is still in pain, there is a referral to a pain management physician. But, often the patient's surgery is recorded as successful.
I mention this not to discourage you but just to say go into this with your eyes wide open. Some surgeons have a tendency to make a fusion seem like a simple solution to the patient's pain issues. But it is important to know that any back surgery is quite different from a regular operation such as an appendectomy. In that sort of surgery, the patient goes to the hospital, has the surgery, is in some pain during the initial healing process, but then heals and is able to resume his/her usual routine. Back surgery for most people is a life-changing event. The surgeon cannot restore the patient to the way he/she was prior the the injury or the advent of pain; he can only perform a procedure to hopefully less the pain, and to stabilize the spine if necessary.
Recovery comes in baby steps...and again, I am speaking in broad generalities...but it holRAB true more times than not. Once the patient recovers from the surgical event, there is still much healing left to be done. In some cases, muscles that have been overcompensating have to learn a new position, a new way of helping to hold the individual upright; the person neeRAB to train himself to use proper body mechanics and posture so as to create a more healthful environment for the spine, etc. Nerves may need to learn new positioning, depending on whether they were compressed prior to surgery or moved during surgery. I could go on and on, but I'm sure you get the point!!
I cannot speak directly to the XLIF compared to other ways to access the spine, like ALIF and PLIF. You can find information about it on the Internet and on forums like this. I would encourage you to read up on it and also do some research on your surgeon. You want to be as certain as you can that he is recommending the correct procedure for your particular issues. Do not assume anything. Do your homework. You really only have one chance to get this right. Once a fusion is performed, it is not going to be undone!!
Again, welcome to the board. Please post with your questions and concerns. There are many merabers who have faced the same decision and are happy to share their experiences with you.