Digital Foundry has already had a look under the Destiny beta's hood and discovered mostly good things.
You can read the full breakdown here but these are a few choice quotes summing up whats been learned.
It remains a sight to behold for all the right reasons; the 1080p resolve on PS4 is intact of course, as backed by the FXAA post-processing seen in the alpha. For the sake of presenting Bungie's gorgeous skybox designs, plus the vast acreage of Old Russia as seen from the highest points, this pixel count does the game a great service. Detail is rendered from a great distance while outside - with little pop-in aside from small rocks and rubble fading into view while boosting with a Sparrow.
Exploring the gloomy, interior areas shows off the game's dynamic lighting in the best manner, with lens flares and light coronas still making the grade. Little has perceptibly changed from the alpha in this area; character shadows blend seamlessly with the scenery, while all objects benefit from ambient occlusion to add depth. The faint dithering to our character's silhouette is still in place from the alpha; a minor blemish to an otherwise impeccable lighting engine.
Unfortunately, the beta version of Destiny continues to show signs of an uneven spread of frames, which while averaging out at the promised 30fps, produces a judder sensation to lateral camera movement.