The first five minutes of the show really compelled me and somehow made me believe that they'd pull it off without the great Charlie.
A couple of scenes later, i'm looking at this dull character; Walden Schmidt and just thinkin' how the show has lost it's glory.
At least @ Charlie's funeral the women he'd slept with made some witty comments and jokes, and the Harper family was hillarious. And somehow just the presence of Charlie Harper made the whole scene indulging and funny, even though he wasn't even there; That's the effecthe has.
Don't get me wrong, I think Ashton is a great actor; done a couple of fun movies and That 70's show will always be a diamond of a comedy. But all his actions and jokes feel kind of enforced, and he doesn't fit in well with the surrounding and the rest of the set.
That can however be due to the fact that we're all suffering from the Charlie-Sheen-sympton. He's been there, and he's done that. And my has he done it better than Ashton.