Pros: cozy for baby, quick, space-saving, cute, comfortable, easy to clean
Cons: not adjustable
I throw on my hotsling first thing in the morning and forget about it until I'm looking to free up my hands while still carrying my newborn or toddler, or both! Then, I just pop said kid in and go about my business. I really don't know how (or why) people carry around little ones all day and try to also get a few things done without one of these. I also have a Moby wrap and an Ergo carrier, both of which I really like and use, but if I could only choose one, it would definitely be the hotsling, for its versatility, speed of use, comfort for both baby and mama, stashability, and ease of cleaning. I can wear it with my twelve-pound newborn sleeping in it for a few hours straight before I need a break. (It is key to get a sling that is big enough so that you can stretch it over your shoulder, so that it doesn't rest solely on your neck.) I can put my two-year-old in it (similar to carrying him around on my hip, but much easier) when I'm shopping, or he has tired from our walk a couple blocks from home, and we can both enjoy our activities in comfort. It is 97% cotton / 3% spandex, weighs little, and takes up no more room than a hand-towel. I never have to lug those ridiculous car seats around, and I just feel bad for all the other parents out there who are carrying those awful things when baby and parent would probably both be much happier in a sling.
In addition, slings are much cuter than other carriers. I grab them at garage sales and second-hand stores all the time (especially now that the company is out of business due to an unfair backlash from the Infantino sling recall a couple years ago), keep an extra one in my diaper bag, one in my car, and have a couple ready in the event a blow-out claims a sling victim. The only quasi-negative about the hotsling is that it's fitted, not adjustable, so I have to have different sized slings to fit the different people who care for my children (husband, grandma, etc.), but I have tried adjustable slings, and I prefer my fitted hotsling, because it is more comfortable, stabler, and leaner.
Both of my babies have spent the majority of their infant days in a Hotsling!