If you're comfortable with the fare I'd grab it. Dallas is pretty easy to make connections now with the new Skytrain that runs between concourses if you have to switch.
As far as American, yes, they're an okay airline. They're one of the "major" or "legacy" carriers and have been around forever. Like most airlines, you'll run into some great flight attendants and customer service people, and some not-so-great that just go through the motions.
Be aware that if you're booking for next summer, your flight schedule will probably change multiple times. When we flew American in May we probably had 6 or 7 schedule changes in the 9 months between booking our tickets and our trip, but we arrived in Orlando within 15 minutes of the original time. Just keep an eye on your reservations, because with schedule changes (which can include a change in plane type) you could lose your reserved seats. You can just go back in online and re-request seats or call customer service to get seats re-assigned.