The bottle works fine but the plastic used to make the top part ...
357051
The bottle works fine but the plastic used to make the top part of the bottle is extremely brittle. I am now on my second bottle both which cracked after dropping one time and my wife's also cracked in the same place.  It seems like its made poorly so you continue to buy new bottles, they need to sell replacement parts or make them better quality.
3740139
I really like the bottle but the clear plastic lids broke on both of my son's bottles.  I tried to call the company but the wait was just too long.
4835352
When I got this bottle. I quite like its performance of thermal insulation.
But I can't imagine that the plastic part and the stainless part of lid were glued together with so poor quality. So I returned this bottle, and have to buy a new one.
1809279
I have had one of these for the past year and loved the fact that it was glass rather than plastic.  I didn't have any issues with smells/mold.
I accidentally dropped my last one outdoors on a cold day on the cement and it shattered.  Bummer!  If you drop it just wrong and the glass hits the ground it'll break.  I got another one, but have decided there's one thing I don't like about the bottle- the lid.  The flip top cap is fine, but it is soooo easy to cross-thread the lid on after filling it up, so the second that you do, you look like a fool because you just leaked water all over yourself since you have to tip it upside down.
4284576
Seals a glass bottle well, but I worry about the plastic eventually breaking.  I wish it was all metal.
144768
Love the bottle but I hate the screw top and will need to purchase another top with a flip cap or straw or something that doesn't require 2 hands all the time.
344621
The glass bottles are good.  The plastic part on top isn't functioning very well.  Replacing those with the ones from the "method" one time use bottles I take from work as they run empty.

Disappointed because I bought these for the brushed nickle look and have to replace with the generic white foamers.
3790711
The straw cap worked fine at first, but the more you use it the more finicky it gets.  The seal between the straw and the lid lets in air unless the straw is positioned perfectly, and it frequently loses suction.  We bought two of these, and my wife is having the same problem.  Great bottle - but get the flip top instead of the straw lid.
3406440
This ultrasonic cleaner is a bargain, but beware that the window in the plastic lid is made of a kind of plastic that can be damaged by alcohol.  If you are just using soapy water as your cleaning bath, this will be no problem.  I sometimes clean small electronic circuit boards in alcohol, and the vapors cause thousands of tiny inner-surface crazes in the top window of this unit.  Also, if you touch the inside of the lid window after cleaning with alcohol, you will find the surface of the plastic is softened by the vapors.  It re-hardens as the alcohol evaporates out of the plastic, and this  alcohol softening of the top window has not been a problem for me.  The inner basket is not alcohol soluble, so that works fine and that's all that functionally matters.
1171512
I gave this product 5 stars because it's everything it says it is particularly the insulation feature.  However, there is one thing I didn't like about it and that's the top(s).  The cap is fine, but the straw mechanism isn't.  I have to fiddle with opening device in order for it to work and make sure it's fully open.  Otherwise no liquid, just airs.  Because I am a biker, this is not optimal.  Fortunately, my old bottle's top fit this new bottle and all's good.
2778749
The connector between the top and the bottle is weak and will eventually tear so I recommend you just cut it and avoid losing the top.  It's not a deal breaker because the top can still rest on the little notch so you don't lose it while using the bottle.
3694877
A few weeks after I bought it I found that the plastic cap part of the water bottle had a crack in it, and leaked water. I was very careful with it, and even glass part of the bottle wasn't harmed at all. Only the plastic cap was broken.
4470199
I like the size of the bottle and that it is made of glass.  I am not impressed with the cap.  I'm not sure if I received a defective cap, but the silver part of the cap is no longer attached to rest of the cap.  Sometimes when I open the bottle, the o-ring seal and insert is detached.
665532
what can i say, it's a glue bottle that works. the plastic cap is on a thin strip of plastic and broke off pretty soon after i got it so it defeats the purpose now. lol
1799898
The bottle itself is good quality and keeps my cold drinks cold for as long as expected. The flip N sip top on the other hand is terrible.  It is uncomfortable to carry by the ring handle.  The valve is hard plastic so watch out sipping from it when you are on the move.  It started leaking after 3-4 weeks from the valve joint.  I bought the bottle specifically for the straw top and it is just terrible.
2037604
The plastic part separated from the rest after a drop.  Still usable just separates every so often.  Filter works well.  If you don't like squeezing the straw to drink this is not the bottle for you
3441224
Replacement the for our same model that's 3 years old. Eventually the acid in the wine wears down the plastic at the spout tip. It does work great but it leads me to wonder if I'm ingesting plastic.