X7's physics were not much better, to be honest. They were in fact, broken. You could not dash wall kick properly. X8's physics were not an issue, its just... other things that were. I could name a few, but the biggest is bland level design with very little replay value. Trillobyte's is the worst offender, using the gimmick of the giant Mechaniloid to repeat the short stage twice, back and forth, with 2 quick miniboss fights with it, and then a really weird miniboss section with random crystal wall dodging. (and not to mention TWO- not one, but TWO ride chaser stages.) Only Stages that were any good, were the Primrose, and a LITTLE bit of the Booster Forest and Pitch Black. Neither was perfect, but were alright for certain aspects. Particularly Pitch Black's Metal Gear X stealth aspect which was interesting and fun to play around with as Axl.
And Jakob was alright, if only for the novelty of the concept, and the execution, which was well done. (you actually see the sky get darker outside as you get further up in the sky)
And I would say that X8's music is "generic" rock. Most of it was forgettable outside of a scant few tunes.