I don't have one, but a number of people in my local ham club have them. My favorite quote is from a very competent guy who does a lot of work on our club's repeater systems. He says they've been thoroughly "Muntzed". If you don't get the reference, see
http://en.wikipedia.org/wiki/Madman_Muntz . Earl Muntz was a self-taught electrical tinkerer who famously took out pieces of TVs until they stopped working, put the last piece back, then figured the missing pieces must not have been needed. He sold TVs based on the the stripped down circuitry. They'd more-or-less work under good conditions, but in fringe areas, or around RF interference, they didn't work well. Or if you put two of them near each other (for example, back-to-back in different apartments sharing a common wall), their unshielded local oscillators would radiate and heterodyne with each other, making both of them have lousy reception.
My friend's assesment comes partly from a teardown, and partly from experience taking one of them up to various mountaintop repeater sites. With all the RF around from various transmitters at different frequencies, his Baofeng becomes deaf anywhere near the mountaintops, as the various strong signals swamp the front end and desense it. His radios from more established Japanese makers work much better under the same circumstances.
Although he criticizes that aspect of it, I nearly always see him carrying his Baofeng. And he does say it works well down in the valleys far from the repeater sites.
It would be interesting to see Dave do a teardown of a Baofeng versus a more-or-less similar Yaesu/Icom/Kenwood.