His views mean diddley-squat. You're thinking like a liberal -- wanting a judge to be an activist, just as long as he's activist your way. The only two questions that really matter are 1) does the judge follow the law and the Constitution? and 2) what is the judge's opinions with regard to stare decisis?
The first question is by far the most important -- if a judge strictly follows the law and the Constitution, then everything else will sort itself out. A judge who will uphold the law, even when it disagrees with his personal opinions, is definately the sort that belongs on the USSC. As far as stare decisis goes, this is where you get the differences between the Scalia and Thomas schools of thought... should the USSC reconsider its own decisions? On the one side, it is easy to point to bad decisions like the recent Kelo case as an example of why stare decisis shouldn't be so important; on the flip-side, a USSC that holds little or no respect for previous decisions makes for a less stable legal system, because there's an air of "at whim" out there. In my opinion, some form of balance is needed on this point -- respect precedent, but reserve the option to revisit controverisal cases, especially 5-4 decisions.
Back to Roberts... his history shows that he's good on #1 -- he's not an activist, he follows the law (look at the infamous "french fry" case for an excellent example). I haven't seen or heard anything with regards to #2.
The first question gives rise to endless questions that we do not know the answer to. Does he believe that we should attempt to interpret ambiguous words and phrases that appear in the constitution, or does he think we should ignore them. Does he believe that historical evidence should be used to discern what the Founders thought the words in the constitution mean, or is the relevant inquiry what the general pubic meaning of the words were at the time. At what level of ambiguity does historical evidence become relevant?
There are many more questions I can think of regarding his personal views on interpreting the constitution that have nothing to do with his personal views on politics.