Ok, just to alleviate some of the terrible rumors and opinions about this game. All of my information is from (a) the designers of the games themselves, taken from the interviews posted on Gamespot, and (b) the dev comments made about the background systems involved in the Glassbox engine.
City Size; The one fundamental reason that they decided on the city size cap is that this game, unlike all other past SimCity titles, simulates every citizen of your city continuously. This means that they go home, commute, work, and play in a simulated fashion. What that means is that instead of cars magically appearing at intersections to show congestion (as in past titles), you can track the cars as they drive throughout the city without them magically despawning (until they get to their destination).
Now, where past SimCity titles have made extensive use of size and scale, this version is significantly deeper. The whole concept of specializations and inter-region play is meant to simulate your average metro area. Where I live, D.C. metro area, there are over a dozen municipalities within a one hour drive, each with their specific industries, facilities, and management. Even the largest cities in America are rarely above 200 sq miles (NYC is 303) and that one is actually five separate municipalities incorporated into one consolidated city. The only major criticism left then would be the arbitrary square boundaries which are mostly due to limitations of the engine.
Simulation Depth; Expanding on the above concept, the team wanted to make your independent cities feel distinct, while maintaining regional cohesiveness and keep the whole thing entertaining. Because Jeff chose not to beautify his city, he put a ceiling on the overall quality of the residents who would move in. This point was elaborated in his second city, where he couldn't understand why placing beautification and entertainment suddenly made people like living there. You can make a crappy coal mining town with low tax rates that encourages poorer Sims to move in, while exporting that coal to more luxurious towns with massive technology and parks. Just go watch some of EA's videos and let them coach you through the diverse ways you can change your city. Most of these factors are not hidden, but rather simply kept under the hood, accesible from a few quick mouse clicks.
Future Expansion/Modding; EA has already announced that there will be extensive mod support for this game, just not at launch. I suppose this is something that one could be critical about, but hey, they have a vision of their product and deserve to let the consumers speak with their wallets about what they desire. If you are complaining about the size size, then build a mod for it. It's that simple. I imagine the average user will simply take what they are given and never change a thing, but there are always the idiosyncratic gamers, which I imagine are represented in higher than average numbers on GiantBomb.
Seriously duders, just give this thing a shot. At the very worst, you get a reminder that your childhood was way better than the kids these days (and you get to complain like your grandpa). On the flipside, at the very best you get one of the best simulations likely to grace the market for a long time to come.