CF is right, but to help you decide:
1. Is the extra cash likely to mean more than the loss of space?
2. A ground floor flat is better to get out of in a fire, but a first floor is better for security - windows open at night for example - which matters most to you?
3. Will you feel restricted by the smaller space?
4. How often do you have other people staying with you, or visiting?
5. Can you get all your furniture in?
6. What are the neighbours like compared to the old flat?
7. How convenient is it for shops, transport, parking etc?