Yes a safe area.
Very handy for Tower of London, Tower Bridge. The area to the north and west (city of london area) can feel a little deserted at weekends because this is the financial hub. That said, sometimes a lack of people is enjoyable in London!
Borough market in easy reach for fancy food shopping / grazing, lunchtime 'street food' and places to eat of an evening.
The location (IMO) only a problem if what you want to see includes mostly stuff in the west and central areas of London (and spread across a wide area). London is absolutely at its best when walking between sites, but the tube is good for moving quickly over longer distances. Buses / boats also worht looking into to decide if this location works logistically for you.
We stayed at the Leonardo Royal London Tower Bridge hotel, just a block from the DLR and 2 blocks from the Underground station. 20 min DLR ride out to the Excel. Close to the St Katherine's marina area and several pubs, ethnic restaurants and a few grocery stores.
Good location to be in the city and getting to the Excel, where we were attending a conference.