We had a bad experience with this that really left a sour taste in my mouth.

It's hard for us to both be available on the same weekend because we're in a long distance relationship (different states), and my fiance is a doctor in his residency, so he does not normally get weekends off unless he requests it well in advance. We were matched with a couple who said they understood our schedule and would work with us.
We both had the entire weekend off on the weekend of Mardi Gras, so we contacted them to see if they could meet with us at all on Saturday or Sunday, at any time, even just for an hour. They said no, that they had things going on that weekend.

The following Monday, my fiance realized he would also have the next weekend available because of a change in schedule, and so we contacted them to ask again if they could give us any time that weekend. One of them texted my fiance and said "Not sure - I'll get back to you." My fiance told him it's unusual for us to both be able to be available and in New Orleans all weekend, and it's a long drive, so we were really hoping that we could get as much done as possible when we did have those opportunities.

Well, then we get an e-mail from our priest indicating that they basically told him that we weren't making an effort to meet them at their convenience and that it was hard to work with us because we said that "Sbelle lives so far away and the drive is too difficult for her to make." We never said any such thing, and I want to stress that not once did they ever offer us ANY time at all to meet with them or make any suggestions as to when they might be available. They were just looking for a way to back out of the commitment they had made to train us. 

The priest tried to find another couple but they were already training two other couples and didn't have time to take on a third, so the priest decided he would just go through the material with us. I'm happy with that because I really like him, but the experience we had with the couple who volunteered to train us was hurtful and frustrating. I would have had no problem if they had just admitted early on that they were in over their heads and, after thinking about, actually were NOT willing or able to work with our schedule. But instead, they went behind our back and told the priest a lie about us, and it just really bothers me.

Anyway, that is just my two cents! I'm glad other people seem to be having a good experience with it!