I'm currently on Remicade and have to say that for a while I was feeling great.
I started out on a low dosage (3 vials, not sure how it's measured elsewhere) and felt good but a few months after the first initial doses I had a really bad flare up and ended up back where I started. After the flare up was treated, they put me on the maximum dosage for my body weight.
It was working well but now I seem to have a very short "shelf life" in between infusions in which I actually feel good.
It does have some side affects, some of which are ironic. I have joint and skin problems now. They call it drug induced lupus (I may be incorrect here) and psoriasis. I also get infections extremely easily. I've had facial cellulitis twice now do the lowered immunity. That is not fun.
Keep in mind that Remicade doesn't treat all the symptoms of Crohn's but it should (fingers crossed) allow your friend to feel some relief from a majority of them.
For me, right now, the benefits from Remicade outweigh the side effects. I don't know how much time I have left on it but I can honestly say that when I was feeling good after an infusion, I was feeling GOOD. Better than I had in years. As Tots mentioned, alot of people will build a tolerance or their body will start rejecting in. Some people are on it for years, others just months or less. Different for everyone.
When they say to be careful if you are sick or have an infection, they mean it. Make sure your friend pays attention if she has an infections (abscesses included) or fevers.
As for the actual infusion, it was way less scary then I was prepping myself for. I wasn't sure what to expect but honestly it wasn't bad at all. I don't take any premeds at the moment other than tylenol. I usually sleep or watch tv while I'm there. I feel headachy and a little "wonky" the day of but a day or two later I start to feel it working. It's a good feeling.
Hopefully this helps a bit