The service isn't as bad as most people seem to think. No, it isn't the overly nice service you get so many places these days, and the staff isn't going to hold your hand. But there's a big difference between the service at Vientiane, and if you have a bad/mean/angry/whatever waitress at Denny's. Vientiane is business-like, but they've always been nice to me. Maybe if you don't go in there and get huffy about the service, they're nicer?
Either way, Vientiane is one of my favorite restaurants. It's so delicious, and I always have food for another meal leftover, and there are so many choices, even for a vegetarian. The Pad Lao is my favorite, I could get it every day.