Sylhet is one of the most beautiful districts of Bangladesh. Its just like a canvas full of green and blue. When you come to Sylhet just try to get the rhythm of the nature. There are beautiful blue hills, small green hillocks, tea plantations, blue lakes, beautiful rivers and streams, waterfalls and forests. If you come to Sylhet must have at least 5 days in hand, rather I would suggest you should stay here for 15 days to feel the real Sylhet.
And its also a very safe place so dont worry at all.