This spell seems pretty good, even in a vacuum (without dragging people toward a hole, fire or whatever).
Moving melee ennemies, even for 5 ft, means they will have to use 1 action to come back in reach.
It can be use as part of a combo with another spellcaster to blast more effectively (a fireball as a 20 ft burst radius, so casting a gravity well before your ally cast a fireball might bring some more ennemies inside fireball radius), or with a previously cast Wall of flame or similar spell.
It's also useful to cover people's retreat and avoid potential AOO.
As a wizard, it will become one of my base spell for a while I think (when you have access to 5th lvl spells and above)
