Tough to compare if they are *better*. They are different. The new workouts are a little shorter but still intense. Upper body plus and Total body plus are both great weight workouts w/ different versions of dips, pushups, and pullups. They aren't as *heavy* type weight training, a few exercises you pick a weight to use for a minute instead of doing 8-10 reps, etc.
Kenpo Cardio + is a TON better than the original Kenpo and I really like Interval + also. I LOVE the Abs/ Core+ workout, it really kicks butt. Really cool moves some using the bar (hanging, using your core strength to lift your legs, bicycle, up & over, etc).
I am doing a Doubles version of the X+/X and am really loving it so far! That way I can still get my running in and am training for a triathlon. I still love the original X weight workouts so this way I can incorporate the new workouts in!
Hope that helps!