I like the shape. It does look like a megacontinent from the silhouette. There are few things that strike me as odd, such as the fact that you have desert, forest, and tundra all at the same latitude. Or that your tundra (which is a very dry climate) is closer to the coast than the forest below it (a wetter climate). The trees get more sparse towards the mountains in that forest, but in real life, the runoff from the mountains would probably encourage the opposite.

Looking at it on the whole, it seems very "snes rpg" chunky - like each area has to be defined by a unique climate feeling. This lets your players travel through many exciting terrains as they journey across the continent, but big chunks of stuff like that aren't very realistic. Look at large climate zones in the real world - there is always a geographical reason behind them - for example, the Amazon is in a huge drainage basin.

It's good that you're designing things with an eye for geography, and I agree that your mountains and rivers look good, but now you should start to think about such things as what hemisphere of the world your continent is in, and elevation and weather (temperature and moisture) as they relate to creating climate zones. Strange as it seems, you can also consider history in shaping climate, to some degree. Was an area deforested by a civilization to build their cities? Or perhaps agriculture has converted farm-able land into desert over centuries (such as what has happened in the Middle East)? Such things can help you rationalize exceptions to the norm for reasons other than magic.

The biggest disadvantage to your current layout, however, is that since each area is a single climate type, it makes the map look smaller to someone like me who expects regions to contain two or three climate types a piece. One thing that can help your continent look huge is if it contains multiple deserts, or large forests, or hilly regions. Makes the viewer think "look how much stuff there is!"