Well, Ermita is always known to be colorful. I have lived in the area and I never felt unsafe but then again, I don't have kids. Yeah. It may seem dark with sketchy folks but Manila is no different than other cities with depressed and nice areas. I recommend you perhaps stay in Makati next time. But truth be told, it won't perhaps be as affordable as my place. As for the park, it's a Christmas carnival. Most of the year, it isn't as noisy.