Hi, I have severely treatment-resistant MDD and OCD. (I've even had my genetics looked at and my doctor confirmed that I have the gene most often linked to TRD, among others.)
I finished my course of TMS earlier this year. I felt a bit of a boost of hope and happiness around week 2-3, which then quickly faded. Nothing else happened on the depression side of things. As for OCD, I can identify that period of time as when I started feeling relief from the anxiety, but I'm not sure how much of that was from TMS rather than meds and my DIY exposure therapy. I have memory issues (that I believe is a side effect of the long-term depression), so that's the most I can remember at the moment. Sorry if it's not very insightful.
Something odd that I liked about TMS is simply the fact that it meant I had to leave the house every day (aside from weekends.) Even if it was just a drive to and from the clinic, it was a new routine and enjoyable.
As for any other lingering effects, I began to have occasional twitches in my limbs. Extremely minor, to the point it took me a long time to even notice them on a conscious level. They were worse right after a session. After finishing the course, I think they calmed down then went mostly away. Then one of my meds was upped and I developed them again, but that's a whole other thing I believe is unrelated to the TMS.
I started on ketamine therapy less than a week after finishing the TMS course. I've been doing that since... I wanna say the end of May? It's not really helping much. But I have to admit, the k-hole is fun, and I have the money, so...
The clinic I go to wants me to start TMS again once insurance's required waiting period between courses is over. They said the plan is that I'd be doing ketamine and TMS as the same time. I have a bit of hope for that, I guess. I think my only option after that is ECT, but I'm not sure if that's even available near me.
I'm being brutally honest, but don't let any of this scare you. Everyone is different. Negative side effects of TMS are rare if your clinic is competent (I was told by the doctor handling my mapping that Wellbutrin has more risk for seizures than TMS.) If you have the money and means, trying it is better than trying nothing at all. Worst case scenario, nothing happens. Best case scenario, your quality of life is vastly improved and you go on to live a beautiful life.
I wish you luck with whatever you choose, and I hope it works out for you.