I just started on my 4th week as well. I've had pretty much the same experience as you, sore as hell at first but feeling pretty great now without much soreness at all. I expect I might get sore again when I get back into the new strength training workouts next week.
I've been following the recommended diet plan fairly close since my wife's doing it as well and does all of our food shopping and most of the cooking. It really hasn't been that hard and like you, I look forward to the workouts now as well. Well, I look forward to the feeling after the workout really, especially the yogax, I feel like a million dollars after that one.
I'm definitely planning on the full 90 days and might even go another round of it starting in Jan. Definitely seeing results in the way my clothes are fitting and the scale's telling me I've dropped 10 pounds as of this morning. Started at 186 and I'm aiming to get to 165 by the end.