Generally, they are the same meaning.
你觉得怎么样 is more oral and people are likely to use it in daily life.
你觉得如何 is more formal and often used in literacy or to show your respect and polite. when you ask for suggestions from somebody who is older, and has higher social status, you can use this to show your respect. In that case， it will be better if 你 should be exchanged by 您.
你觉得怎么样 is more oral and people are likely to use it in daily life.
你觉得如何 is more formal and often used in literacy or to show your respect and polite. when you ask for suggestions from somebody who is older, and has higher social status, you can use this to show your respect. In that case， it will be better if 你 should be exchanged by 您.