Although Drac X PCE is still my fav "Castlevania" game, XX is a decent game in it's own right.
But after playing the PCE version on a regular basis up to the SNES game's release, I was very frustrated by some sections in the SNES game where a single hit from an enemy could juggle you around from full health to death, all without being able to do anything to recover.
I haven't played through it since(I did finish it at the time), but back then I figured that it was level design that didn't take into account the character gameplay ported from the "original".
So at the time, I didn't really like it, nor hate it(but I've always loved ports in general, good or bad).
I like to think that I'm more objective overall now(although still PCE-crazed) and beleive that its simply a good-above average game, but not too high up in the Vampire Killer/Akumajo/Castlevania hierarchy.
Aesthetically, they went from a cool(blues, greens, purples, etc... not "wicked-awesome!") dark colored theme to pastels and SNES'ish graphics(with at least one Mode-7'y bg).
And although the music does sound really cool as a CD-SNES port, its not really as-good-as-or-better as some game mags have reported.
If you can get it cheap, go for it. But I wouldn't recommended paying too much for it without trying it first.