Overall, we were really impressed. We boarded at the Mount Baker stop and rode south to Tukwila and then north to Westlake over a few hours.

MOUNT BAKER STOP
We never waited more than 20 minutes and the trains seemed to operate smoothly the whole time. Every stop had multiple volunteers and Sound Transit reps, handing out stickers and pamphlets. We saw multiple musicians playing, with 3-4 at Tukwila alone.
Speaking of Tukwila. The building is pretty incredible. It seems almost other worldly, which I think is a good thing. Remember that first impressions of Seattle will be made in Tukwila as visitors take the rail from the airport to downtown.

The station will surely make an impression. I really liked this sculpture:

On the way to and from Tukwila, Mt. Rainier is visible on a couple of occasions. That servers as a nice site for visitors as well, at least 25 days a year anyway.

We arrived in Tukwila at about 2pm and walked down onto the mostly empty parking lot beside the station. To me, it seemed like a missed opportunity to have all those people line up and not have a more fun and interesting atmosphere. I thought the parking lot would be full of food offerings from local businesses, perhaps even games for kids or other resources. We found a yummy hot dog from the Tukwila Firefighters, but that was about it for food.

TUKWILA STATION
It was easy to see that the crowd control was well managed at the major stops. Instead of letting everyone crowd the platform, the crowds were only allowed to go the platforms in groups. This made the lines seem long at first, but they moved quite quickly.

WESTLAKE
The trains themselves are beautiful on the outside and the inside is pretty much like any other train (not a bad thing). I always found a place to grab a bar for stability and there were few unused spaces when crowded. I was surprised at how quite the train was. The voice that tells you about stops says that "doors open to my right."
I really like the little icons for each stop. My favorites are Mount Baker (mountains of course) and the anvil icon for SoDo. The Westlake icon is a crown and I imagine there is a reason why, but I'm not sure what it is. A nice touch would have been lights that highlight upcoming stops on the line.

The Sound Transit Twitter account is reporting that 45,000 people boarded the light rail on opening day. I wonder what today holds?
Two great resources for tracking light rail news: Rainier Valley Post and Seattle Transit Blog.