Yes, Decathlon are normally very good value for money. Particularly if you can get it with the cycle to work scheme as they don't charge any extra admin fees even on sale bikes which is unusual these days.
Personally, I would only spend that kind of money on a mountain bike where the weight and spec are important. For a run of the mill commuter it is probably overkill as they are all limited to 15mph and the weight is largely irrelevant.