We flew Delta from Oregon last January. We had booked about 9 months in advance and paid $236 RT. A few months later they canceled all of our flights and rebooked us without notifying us, and I had submitted my email when I booked. Our original flight left at 1 pm with one layover of one hour, return flight was about the same. We were traveling with an elderly disabled passenger, so flight schedule was important. When they rebooked us, our new flights had layovers of over 9 hours each way and our seats were spread all over the plane (we were traveling with 2 kids under 7 also). I was a bit upset! I called to get the flights changed, and they worked with me but I was limited in the flights I could select because they had to find flights that had available seats within my same category. Since I had paid such a cheap fare, that presented some problems. We ended up having to fly out at 6 am with a 1 hour layover. Our return flight had two stops of 3+ hours each. Our decent 7 hour travel day became 13+ hours. It was a horrible, long, painful (for my mother) day and I would NEVER have booked such a return flight if I had a choice.
On top of all that, when we arrived at 4 am for our first flight (we had printed boarding passes the night before with confirmed seats for all flights), we were told that we were all on standby in our connecting city. Even the ticket agent was confused how they could do this when we had checked in and printed boarding passes. I suspect it had something to do with us being the lowest fare paying passengers. When the ticket agent saw we were traveling with a disabled passenger and two small kids, she got on the phone with the connecting city and spoke to a manager for over 30 minutes to get us off standby.
I have read too many bad things about Delta, and have experienced it enough for myself. I will avoid Delta in the future, even if it costs me another $150 per person, which is what the other airlines charge from our city.
I know it is possible for all airlines to change their flights, but Delta is known for it. Before booking this great deal, take a look at all of the other flight options for your days and ask yourself if you are willing to accept the worst possible combination of those flights. And don't book a car rental until a couple of weeks before your flight in case your arrival/departure times change.