DH and I have both taken probiotic pills before.
In DH's case, he had a stomach/intestine parasite and was taking it in conjunction with olive leaf, where the probiotic he was taking was to help knock back the negative bugs that were being killed and flushed away by the olive leaf supplement. After the parasite was gone, there was no benefit to keep taking the probiotic that we noticed. In DH's case, it was prescribed to him by our kinesiologist and nutritionist, and wasn't a grocery store level supplement.
In my case, I tried taking it as a weight loss supplement when I was also dieting and working out, based on a study I had read showing that women on a restricted sugar diet lost a bit more weight when also taking a probiotic at the same time. I personally didn't really notice any difference after 4-6 weeks, or any boost in my weight loss after I started taking it. Since it was about $20 a bottle for the brand I could find with that number of cultures, I stopped buying it. Find an article about that here, with a link through to the study:
http://www.npr.org/blogs/thesalt/2014/02/05/271153568/ladies-good-bacteria-in-yogurt-may-be-good-for-waistlines-tooAfter doing more research about it, I found that the majority of the freeze dried bugs in probiotic pills don't survive your gut for more than 1-2 days, and don't do much in between when you consume them, and when they die of a hostile environment... Which is why you have to continue taking the supplement. They never 'set up camp'. It takes a high end probiotic (20 billion 'live' probiotic cultures) to ensure you're getting a solid dose of live buggies, and even then, they aren't guaranteed to be alive upon purchase. :) Read the bottle on that one.
I've found that it's a better strategy to try to keep up on my fiber intake, so everything runs smoothly (haha), and to otherwise make sure my diet is balanced. Taking iodine has often helped when indigestion rears it's ugly head.
If you want to learn a bit more about how your internal microbiome works, and how to truly effect it, try reading Missing Microbes. Although the narrative is about antibiotics, it helped me establish a good understanding of how the human ecosystem is established and how to keep it functional.
http://www.amazon.com/Missing-Microbes-Overuse-Antibiotics-Fueling/dp/0805098100Of course, if you're having a specific problem, talk to your doctor. They should be able to help you figure out if probiotics will help solve it.
Hope this helps!