I bought a Decathlon Btwin
I bought a Decathlon Btwin 500SE as a winter bike. Having ridden it all winter I am very happy with it for the price. However, the rear cassette and chain were fscked after 1500 miles. Also the freewheel broke after about a month (Decathlon gave me a new wheel).
So components aren’t as durable as a more expensive bike. If you do a decent amount of mileage you need to factor in the cost of repairs. I got mine in a sale for less than £300. Given the amount of use I have had out of it I think it was value for money. Hopefully, it will survive next winter without needing any major repairs.