Honesty is my policy. However, there's a-many different ways to deliver truth, and although I fail most of the time I do attempt to be subtle, and at least think before I make a statement.
When it comes to forums this process is a lot easier; if I know my opinion could possibly hurt an individual then I will keep it to myself and ignore the thread rather than bashing right into it. Opinions can be great, but I see no need to go poke everyone between the ribs.
As for real life (well, aren't we brutally screwed then?) I am very direct, honest and definitely not liked by everyone, but (similar to the forums) I don't shy away from giving individuals a reality-check if necessary, and would rather be considered a jerk than a liar. If someone asks me for my opinion directly, and I know it will hurt them then I warn them beforehand and ask if they still want my opinion -- naturally the warning itself already has an alike effect, but does confess of some consideration[...]
Likewise; I'd rather be friends with a complete arse than with a liar.