It's not been mentioned as far as I'm aware in the reveal, but I think there still needs to be some way of quickly showing if a system has already been discovered and scanned. Perhaps with a simple percentage indicator telling you what has already been discovered and mapped in the system, alongside you own percentage discovery indicator. Which would at least give you some idea of whether a system has been visited and how thoroughly it's been explored. I know someone said in another reply here, that you can tell if a system has been explored if the main star has been scanned, but so so many of the systems I have flown through have had just the main star scanned and tagged but nothing else in it. I've even found ELW's in systems like that.
Apart from that, I'm looking forward to seeing how the new system works. In my mind the old ADS honk reveals all and point your ship at a planet to scan it job, has only ever been a simple placeholder mechanic, just so that there is something there gameplay wise. I for one, am glad we are finally getting something with a bit more depth to it to replace that. I used to spend entire evenings just scanning 2-3 systems, flying from planet to planet and sometimes across great distances. This will actually make scanning a large spread out system a heck of a lot quicker. Remember that initial scan will now reveal all the same data you are getting currently from the DSS, such as mineral and metal composition, geological activity, and now also other possible points of interest such as Guardian sites, barnacles etc. Then if I spot a planet with something interesting on it, such as geological activity, Guardian site etc, I then can choose to travel to it to make a more detailed map of the surface to reveal those sites. This will actually increase the amount of interesting stuff we can find when we go out exploring now in a big way. How many people have seen planets with geological activity listed, but just ignored it because you'd have almost no chance of finding it, even after hours and hours of orbital skimming? Now we're finally being given the means to be able to find all those sites. Frankly, that's something I've been waiting for, for ages now. So personally all these changes sound great to me, and as far as I'm concerned it's going to be a big improvement over the current bare bones exploration system and I'm looking forward to trying them out.