First time I visited Kempty fall around 8+ years back and that time it was good and really nice place to see. Again I saw this last year. I was shocked to see that place. It has lost it beauty. This place is over commercialized and too much kiosks is there. Various shops have been opened there due to which it is quite hectic to reach that place. There is a small street crowded with people and lots of small shops.
The place is neither Beautiful nor clean. It is a complete wastage of time and money to visit.
Though this place is easily connected with road. One can take state run transport bus, taxi etc to reach there.
Mussorie has lot more places to see other than Kempty fall. I would suggest to visit mall road, Dhanaulti and Kanatal.
Hotels are good but a bit costly during summers.
As Mussoorie is a Hill area and especially belong to Uttarakhand hence don’t worry about security. Local people are quite friendly so don’t worry about security.
I would suggest to visit this place during off season like in September, October and November where there will be less crowd. Prefer to visit during weekdays as most of the Delhi people plan their visit to Mussoorie during extended weekend.