I love this water bottle. Love it! I've had it for nearly a year now (10 months, really, but who's counting?). I wrote a praise-heavy review for it on Amazon when I'd only had it for two months, and I've found shockingly little to complain about in the months since. I take it with me everywhere; it's never let me down, but if it ever does I love it so much that I think I'll buy another right away!
Spill-proof flip-top: This was one of my requirements for a water bottle. My first introduction to water bottles was, believe it or not, a sippy cup. That's right, the bottles your toddler drinks from. My roommate loved drinking from them because they never spilled no matter how often she accidentally knocked them over, and knowing my own clumsiness, a spill-proof design became a requirement in my search for a water bottle. I've never experienced any spillage from knocking over my water bottle.
Straw: Another requirement of mine. Without a straw, drinking water while driving is a nightmare: unscrew the bottle cap, tilt back the bottle to drink (which then blocks my view of the road) and hope it doesn't spill everywhere if I hit a bump, and then screw the lid back on. No thank you! With this bottle, all I have to do is press a button and the lid flips neatly open to reveal the straw. No caps to unscrew, and no messes all over my car (or my clothes) if I hit a bump!
Insulation: I didn't know about this before I bought the bottle, but it's truly amazing how long water stays cold in this thing. I've read reviews claiming that ice cubes were still sitting unmelted in the bottle when someone went to refill it 24 hours later. I haven't experienced that wonder personally (I've never put ice cubes in it), but every time I wake up in the morning to find the water nearly as cold as it was when I filled it before bed, I shake my head in amazement.
Durability: I drop this thing constantly. I work at a kennel and I have had big dogs snatch it from me and play with it as a toy. It has suffered only minor scrapes and still does not boast even a single dent. This bottle is extremely durable, and I am grateful for that.
Sweat-proof: This is one feature of the water bottle that I think I take for granted. It just doesn't sweat. You will never put this water bottle down and pick it up later only to find a messy wet ring on the table. Until I use someone else's water bottle, I completely forget that most water bottles do this. A mild inconvenience, to be sure, but an inconvenience nonetheless. Or it was, until I got this water bottle.
Wide mouth: The wide mouth makes this water bottle easy to clean, and it means that you can add ice cubes to your water, or perhaps a wedge of lemon, if you're into that sort of thing.
Pretty: This water bottle is available in a variety of very attractive colors and patterns. Woo!!
Difficult-to-clean straw: The bottom portion of the straw is detachable for easier cleaning. While this makes the crook in the straw easier to reach, this is still the most difficult part of the water bottle to clean and may develop mold (mine did). A straw cleaner will probably have to be purchased separately to clean this part of the straw. I have yet to discover if it is possible to buy a replacement cap.
Doesn't fit cup holders: Thermos' website claims that this bottle fits most car cup holders, but it certainly doesn't fit mine. Barely. You have no idea how frustrating it is to know that my bottle is perhaps an eighth of an inch too wide to fit my cup holder. Alas, it must ride beside me instead, nestled uncomfortably between my emergency brake and the front passenger seat. (My household has a '95 and '96 Toyota Camry. It does not fit in either cup holder.) However, this obviously will vary from car-to car, as my cup holder does not fit any other water bottles, either. It's a car thing, not a water bottle thing.
(Potential cons are possible gripes or issues one might have with this product, but that I did not personally experience)
Weight: This water bottle is on the heavy side compared to other, non-insulated water bottles, even when empty. Probably not a deal breaker, and not obnoxiously heavy, either. Just... heavier.
Not dishwasher-safe: I ran this through the dishwasher once and the decorative coating began to chip off in areas. The lid made it through without problems.
Lid fragility: I have seen reviews of this product complaining that the joint on the lid is fragile and breaks easily. I have personally had absolutely no problems with this lid or with durability overall, however if one examines the lid it's easy to see where the possibility for breakage would occur. It does seem, however, that you would have to drop it at a very specific angle to damage the joint.
No carabiner: Many water bottles these days come with carabiner hooks attached. This one does not, nor is there a place for any sort of hook on the bottle. You cannot hook this bottle to your belt. In other words, this is not exactly the ideal hiking or camping water bottle.