lmtp327098 wrote a review of Hydro Flask 40oz. Wide Mouth Water Bottle on February 4, 2013
Familiarity: I've used it once or twice and have initial impressions
I was excited to get my Hydro Flasks because I read many great reviews. These containers do not retain heat. As many other reviewers stated, you need to "prime" the vessel by preheating it with hot/boiling water for 5-10 minutes and warm up the food to piping hot temperature. I did all that. I put the food in at 7:30am, but by 12pm the food was lukewarm.
I believe these containers are better at retaining cold temperatures. This did not work for the purposes I needed which was for a hot lunch. I returned them.