While the suicide ending is dark, it's more appropriate for Zira's character. It also proves that she might of had a personality disorder or something though o.0 But yeah, I definately prefer it over "Whoops! I slipped" ending.
..am I jacked up for finding Zira adorable in her suicide? I mean c'mon, you don't see her smile every day and that =D face she makes is kinda cute.