Yes they are excellent choices as organic fertilizers. 

If you use them, use less or no synthetic (commercial) fertilizers. Since coffee grounds lack phosphorus (the key ingredient in fertilizers for flowering plants) it is better on non-flowering shrubs, foliage plants and grass than flowers.

However, if used in combination with phosphorus (e.g. super phosphate or rock phosphate) it is excellent — and cheap. You can buy super phosphate and rock phosphate at garden centers and home improvement centers.

It is not  "slow release" as typical of most organic fertilizers. Most of the nitrogen will be available pretty fast. This means you have to watch out not applying too high quantities at one time, and that more then one application during the growing season may be needed but in smaller volumes at a time