I got my 1996 GS Sport in June and it was serviced in July and Lexus replaced my remote's battery, but recently mine's not been working all the time. It's only on opening it, I've gone to my car a number of times in the last month and pressed the open button to have nothing happen, then after a couple of minutes and numerous presses it opens.
It's very annoying when you're away from home, and I have the Toyota alarm that has a seprate remote, so opening/closing with the key doesn't deactivate/activate the alarm like the previous system with the integrated button on the key.
I've not been to Lexus yet.