It's official: Neil Gaiman is returning to the Marvel Universe, and he's bringing a friend with him. Angela was one of Gaiman's contributions to the early Spawn comic series. The character is an angel sent to hunt Spawn, but the two end up developing a romantic relationship. Eventually, in issue 100, Angela dies helping Spawn defeat his nemesis, Malebolgia. Since then, Angela has remained unused, forgotten by time. Now, Angela is being brought into the Age of Ultron saga as part of the finale. We have no idea how this will work, what role she'll play, but there are rumors she will eventually be brought into the Guardians of the Galaxy series, so there's even a chance we may see her in the MCU. Still, let's lay it down right now: this can either be awesome or it can be terrible.
Pro 5. The Introduction of Heaven in the MCU
Marvel isn't known for its angelic characters. You have Archangel, but he's a mutant. You have countless demonic themed villains, but nothing quite like Angela. This could potentially expand the cosmology of the Marvel Universe, especially if Angela is going into deep space. Are there Hellspawn in other parts of the universe...?
Con 5. She's Out of Place
Heaven has never been a huge theme in Marvel Comics. Mythological deities, hell, yes, but heaven? No. The introduction of this character might force the Marvel Writers to explain her existence, which may require several retcons to both the Marvel Universe and Spawn's story. If mishandled, this can be a huge mess.