Aside from that particular shortcoming, carrying over a character means that throughout Mass Effect 3 he will be having many, many joyful reunions with his former comrades-in-arms. A fresh character has no such (joyful) reunions -- nor does he get to tap the knowledge and skills of his former comrades. Furthermore, if in the earlier games there had been crisis moments where a comrade would die or potentially be saved, or you parted on good terms or bad, it seems that the new Shepard had apprently made all of the Bad Decisions. I think about the only character carryovers from Mass Effect to Mass Effect 3 are Joker (the pilot) and McAdams (the Chief Engineer from Mass Effect, but absent in Mass Effect 2). Others that turn up tend to be aloof and distant.
Undoubtedly, many people will ask, "But what about Ashley Williams?" Yeah, she's there, but she doesn't even remotely look like Ashley, much less act like her. It's like the battle-grizzled, hard-bitten Soldier that Williams was, has been replaced by a swimsuit model that happens to wear the kind of armor a Soldier wouldn't be caught dead in. (Wait, that's not correct. It is that kind of armor, because wearing that kind of armor guarantees the Soldier's head would get shot off.)
3. Granted, putting EDI into a mobile platform is an entertaining, reasonable idea. But did it really have to be a sexbot chassis? (I can just imagine -- or should I say "fantasize"? -- what kinds of devices she/it keeps in her toolkit.)
4. Mass Effect 2 cost $60, but if you pre-ordered it you could get it for $50. With Mass Effect 3, the price is $60 regardless. Given the economy, I see the full price-only policy being justified. But for that $60, the player gets seriously less than what he got in Mass Effect 2. Reflect on all of the different venues you played through in Mass Effect 2. Now consider Mass Effect 3: No Ilium. No Omega. Only about one-half the area in the Citadel. What had been quite large planetary explorations in Mass Effect 2 have become scan-and-drop-a-probe-from-orbit actions that take all of 5 minutes (max) to peform. In Mass Effect 2, for each Companion that joined the team, there was a side mission associated with that Companion for you to play through. In Mass Effect 3, there are no such side missions. In short, there is significantly less to do in Mass Effect 3 than there was in Mass Effect 2. This is easily reflected by the fact that a thorough play-through of Mass Effect 2 took 60 hours. Being just as thorough in Mass Effect 3 took less than 45 (most of which was simply trying over and over again to just survive the mission).