A stove with an integrated electric oven does consume quite a bit of energy when the oven is on, but if you're in a small apartment and don't have room for two separate appliances, it ends up being a practical solution. Its energy consumption is similar to a standalone electric oven, except you take up less space. The upside is that modern ones heat up relatively quickly compared to older models, maybe 10-15 minutes to be ready, depending on the model.
What really matters is whether you'll use the oven regularly. If it's just for baking things occasionally, it makes sense for the convenience. Now, if you cook a lot and use the oven almost daily, you'll definitely notice it on your electricity bill. A lot of people prefer to keep a gas stove for the burners (if you have a cylinder, of course) and supplement it with a small electric oven, because the combo ends up being cheaper at the end of the month.
Another thing to think about: these stoves with integrated ovens tend to be more expensive and quality varies. If you can stick with just gas for the burners and invest in a separate standing electric oven, it might work out to better value for money. But if you really don't have the space, a decent integrated stove solves the problem and it's not the end of the world in terms of energy consumption.