Word for a thing with positive and negative consequences

I'm not sure of a single word. You might use the phrase double-edged sword, e.g.

Taking a cab is a double-edged sword. You don't have to worry about parking, but it is more expensive.

For intermingled positive and negative emotions, I would use bittersweet. Clearly though, the phrase "taking a cab is bittersweet" doesn't really hit the mark, unless you're discussing the conflict of leaving vs going. The best I can come up with is "taking a cab rather than driving has mixed/conflicting/divergent consequences." I'll think more though, those still feel off the mark to me.

If you're saying that two things have the same chances they will turn out well, or both are equally appealing choices, you can call it a toss-up.

"Should we take a cab or drive?"

"A cab sounds expensive, but I'm really tired. It's a toss-up."

Mixed bag:

one having both positive and negative qualities or aspects

Also spelled mixed-bag, to meet the single word criterion.