Rating a beta like this is mostly about trajectory and limits. Is it improving? How quickly and for how much longer? Is there anything in the design that will prevent further improvements?
That said, I think one of the strongest points of FE is the XML modability that it has. It is still in beta and already people are modding in new content, and we don't even have any sort of editors yet. Even if the balance isn't great on release, this detail will likely make it possible to bring the playability up after release, adding all sorts of new content.
Another positive point is the graphics. It is a pretty game at this point, playability aside.
Of course, the danger of having so much content and so many variables and options is it makes it difficult to create an AI that will effectively use those options. You can teach an AI to play Tic-Tac-Toe fairly easily. Teaching the AI the pros and cons of a fireball is another issue. This is the critical issue and is also where the current build still falls short. It has yet to kick my butt in any real sense, and I can easily prosecute a war against an AI that has a much greater power score. This is likely a combination of a bunch of little balance issues in the AI combining to kill it, and hopefully it can be solved. Strategy games ultimately boil down to the difficulty of the AI. As an RPG, however, FE is showing more promise and that is why I still play it. After the exploration, looting and questing is over, however, I usually thrash a kingdom or two and then quit.
I do see the game improving over time and the XML modding ability extends the upper limits of what this game can be. The real limiting factors are things that cannot be modded or balanced, like certain AI elements, pathing, and UI features that should be added or removed to make the game more playable.
For the purpose of marketing, the first couple hours of the game should be the focus. Since that is where more of the RPG elements shine, it is pretty good, though more tech, building, and equipment options early on would help. Reviewers will mostly only look that far, so the game is in fairly good shape in that respect. The ultimate critical score of the game, particularly from players, however, will come from challenge and replayability. If that is not there, it will quickly be shelved and not achieve the classic status that we are hoping for. Right now the RPG replayability is looking good so far, but the strategic replayability is in need of some improvement.