I agree. We've played the Keep on the Shadowfell and it's certianly a lot faster. We got through about 4 encounters in a session. Before it might be 2. This is after the learning curve, by the way.
Herein lies my concern. It seems like it's one kind of abstract math to balance the encounter versus another, Challenge Rating versus XP Budget. I haven't had a chance to try to make any encounters yet, so I'm witholding judgement until after I've run a few.
I must admit that currently I'm liking 4e. Every character has something they can do. The level progression is steeper but each step has something to offer. First level doesn't feel underpowered at least. We've only played up to 3rd level. So we'll have to wait and see what it's like when we play higher levels.