i haven't had TMS myself, although I've met quite a few people at the hospital who are having the treatment. It doesn't hurt, they have treatment twice a day, takes 20 minutes I believe. There's no harm or anything to worry about trying it.
I know one person who goes in to hospital once a month for 3 days top up treatment. Initially it's 4 weeks in hospital for a full round, then maintenance. I've also met another person who only has maintenance when required, which is about 9 months. Everyone responds differently. I haven't heard any bad stories and I've met a lot of people who have this treatment.
I hope this helps put your mind at ease.