I haven't played DSI, my pc can't handle it. NG+ DSII right now.
From the videos I watched, it looks like DSI map design was much better, you could feel the world around you. DSII feels like disconnected levels from a video game. The individual levels of DSII look great, though, but there's very little connection. I don't know if the budget was cut, or they meant to do that in the first place. Maybe they were going for a grand journey across the land, but only the bastile had connections that made sense. One explanation could be that Drangleic is not completely corporeal and space is messed up the same way time is, but that is just lazy.
Can't compare the combat, since I haven't played DSI, but I am enjoying it in DSII. Ivory King's UGS is fun.