Well, in all honesty, I'm only a fledgling Marth player myself, so I don't quite feel as qualified to answer this as I feel CK would be, but I'll just throw in my two cents.
In my experience (both as and against Marth) Marth's comboability hasn't changed to that great a degree, but you're right in that he gets comboed alot more now. Invincibility frames on his up-B really did wonders for his defensive game, though he can still pierce through some crazy stuff with it (in one of the videos, CK interrupted a Falco fair right in the middle of being hit by the move). His increased weight makes spamming shdfair a bit harder than normal to do, though that may just be due to the fact that I'm not a Marth player and haven't gotten used to the new timing. CK rarely does shdfair to my recollection, usually opting for shnair or shfair -> uair.
Speaking of, I find shfair -> uair alot more of a hassle to do, even at a high buffer. Most of the time due to the greater weight, Marth will hit the ground just after the fair completes and just buffer a standing utilt...which I guess gets the job done as well, albeit less reliably. Other than that, his uair still juggles just as well, his fair leads into follow-ups just as well (for the most part), the new bair is a nice gimping tool, and dair is dair, as is nair. Offensively, I don't think he's taken much of a hit, but he doesn't quite have the fall speed to be a blitzing combo king like Fox, Falcon, or even to a certain extent Falco.
Anyway, to directly answer your question, Marth's pressure game probably has been hit a little bit, due to a harder time performing two aerials out of a short hop, so his strikes have to be a bit more precise than before. I'm sure it's nothing a dedicated Marth main can't handle though. Defensively he did take a huge hit with the loss of invinc. frames on up-b though.
Anyway, just my thoughts. Most of it was off-subject anywho. You can check with CK though. He's much more familiar with the new Marth now than I am.