I was on the zone 2/3 East border. A fast-gentrifying and generally very pleasant area to live. The issues with crackheads and public defecation that I mentioned upthread were very real. Not a constant issue, but a regular issue nonetheless.
Another issue was the fact that anything could happen at any time, and quite regularly it did. Including drive-by shootings at 4pm on a saturday afternoon on the local high street. More stabbings than I can possibly count, several fatal. A gun pulled on a man who (politely) asked someone if they could control their feral dog next to a play area. A police car chase down our street where a shotgun was fired. Having to check the bit of the playpark where your kids were running around for discarded needles.
Several acid attacks, including one where the victim lost his tongue. On and on.
But despite all this, I love London and always will. I'm a very frequent visitor. The good vastly outweighs the bad.
However, I was out on a friend's boat on the local lake at 6am this morning. Had the place more or less to ourselves. Even in the busy periods (I'm in the Lake District) stuff like this is very do-able with very little effort.
No regrets about leaving, at all.