Cheaper NCF, channel moving option, unlimited external recording without any recording top up, good PQ of HD channels, transparent logo are some of the advantages of Sun Direct. The usb port is in the front and the stb can be used as a media player i.e, can play the content from usb storage devices.
Poor PQ in SD channels, non universal remote are the biggest disadvantages. Landing channel always shows Sun Direct HD Tamil channel which is an irritating factor for non Tamil users.
Please take a look at the below post where I have shared my experience regarding the picture clarity and audio quality of the HD channels in the Sun Direct HD connection that was installed on November, 2021. I hope that review would help answer few of your queries.