I’m using it and I think it’s great. Just one example to illustrate this:
The following model at Sketchfab is very complex. The original OBJ file is 186 MB big, the glTF version about 41 MB. Although the usage of glTF clearly reduces the file size, it’s still bad to load this amount of data over a potential slow internet connection. After applying Draco with default compression level to the asset via gltf-pipeline, the file size is reduced to approx. 5 MB. Of course you have now a higher client-side parsing overhead because of the decoding process but the overall delay is much better than before. Nevertheless, for such big models I would recommend to perform the decompression in a worker. Besides, using a mesh compression algorithm like Draco is more efficient than using a general purpose, lossless compression like zip.
Decompression can be a quite computing intensive task. The official Draco libs allow a decompression via JavaScript or WebAssembly. The latter one is the faster approach.