I think the ending of X tv was too simple...

Yes, X tv, movie and manga all end differently. 
In fact the ending of the manga has not been 
published yet (when CLAMP stared it in 1992 they 
said it would end in 1999 ! 5 years later it's 
stil not over...), but they said the ending 
would be different from the tv series and the 
movie.

I just read volume 18 of the manga, it's 
surprising. Seichiro was killed by Subaru, just 
like in the series (in volume 16), but then Fuma 
offered Seichiro's eye to Subaru, who accepts 
(because they loved each other in fact), and 
inherits of the powers of his former enemy. 
Subaru has now 2 eyes again, he is the new 
sakurazukamori, dressed in black, and will 
likely fight against Kamui ?!? Really leally 
looking forward to the newt volume...