I need more info on the following subjects to have a solid opinion on 4E:
1) Will 4E be 100% playable without subscribing to D&D Insider?
2) How different would 4E be from 3E? Would that difference be worth the investment in 3 new core books (circa 100$ in total?)?
3) How miniature/skirmish-heavy would 4E be?
4) How useful would be my 3E sourcebooks (such as Lord of Madness) with 4E? How easy would it be convert stuff between 3E and 4E?
5) How focused would the game be on combat as opposed to other challenges (traps, exploration, stealth, diplomacy)?
6) And, most importantly, how would the overall 'feel' change?