Sorry for the long winded answer but I wanted you to have a more detailed view of why I bought CampInn and how my view has changed over 2 years of ownership.
First, I wouldn't say any major negatives. I think the way I would explain it is that there are 2 different types of areas of challenge/issues...general teardrop camping type challenges and CampInn specific design choices.
However, let me preface some thoughts here. I am an Engineer by trade so I always look for ways to improve. I am also the kind of person that researches EVERYTHING in detail before I buy anything....it does not matter if it is a $10.00 USB cable or a $20K trailer. It's just my nature so I spent a great deal of time looking at trailers of all types before deciding on a teardrop and then spent even more time researching teardrop vendors, looking at a bunch in person before deciding on CampInn. From a quality perspective, there was a significant difference in quality between different manufactures and CampInn had the best quality of build I saw. I think their quality was even better than many, many of the full trailers I checked out. I am still in awe of the build quality of this trailer.
My wife and I actually considered building our own as we have a woodshop. However, one thing that is a real advantage with CampInn is that you can see some of the evolutionary changes that they have worked into the design that we would not have thought of on the first couple of builds. For example, in the galley, they have these channels built into the storage bins to funnel water out so it does not drip into your storage area. Imagine you are working in the galley and spill something wet, the gutters built into the storage area channel it away. It's detail things like that throughout the trailer that you learn over time you need. Because CampInn has years of experience and customer feedback to work from, they solved many of the issues that would take a home builder to resolve after a few builds.
Also note, that since I bought my trailer used, I did not have the benefit of going through the orientation and some of my comments may have been addressed by going through orientation with the CampInn team.
So, let's talk about the different challenge types.
CampInn Design Specific Choices
I think there are some things I might have played around with from a design perspective. For example, the stove is set back in the galley. Now, this has pros and cons. Being at the back of the galley, it helps protect it from wind while cooking so you don't have the burners going out. However, being at the back of the galley, if you are cooking in a deep pot, you have to lean over a little to see inside...this might be more challenging if you are vertically challenged. So, I think if I were building one from scratch, I would play around with different placement locations for the stove to see if there were alternative locations that might work. It may be that this is the most efficient placement because there really isn't any wasted space in the galley.
The hatch design and prop mechanism in the galley are awesome. Again, I think this I a reflection of just how bright the engineering and design of CampInn team really are. With that said, the Galley Hatch might be a little heavy for some. I won't say that it is a struggle to lift, just that it is solid and therefore, a little on the weighted side. I have thought that adding some gas struts to help make the latch easier to lift might be nice. I would not use them to keep the hatch open, just aid in the opening and closing. However, I don't know if this would impact other aspects of the design so I would need to study this more.
About the only thing I would like to see improved is the locking mechanisms. This may be more of a reflection on the locking options provided by the industry than a CampInn choice as they can only choose from what is on the market. The locks function fine, I just think they could be a little more snug.
I do wish they had a fully stainless steel option but having worked with stainless steel, it is a massive pain in the arse to bend, cut, trim, etc. so I totally get why that is not an option. It would also add considerable weight to the trailer which would impact gas mileage, tongue weight, etc.
Teardrop Camping General Issues
Not having a bathroom or shower, might be a negative for some. For us, just building a side entrance tent and putting a Luggable Loo in solved that issue for us. For the shower, we have a separate shower tent and working on getting a hot water heater.
The tent also solves an issue of getting dressed. It was a little inconvenient to get dressed lying on your back but the tent fixed that as well. I have a separate video on our side tent if you haven't seen it, it might be worth watching.
Outdoor cooking might be both a negative and positive. Negative because you might have to cook in inclimate weather. Positive because you are cooking outdoors, no lingering smells in the trailer, etc. To address the bad weather issue, we have 2 different canopies. One for fair weather camping (Quick Shade Summit 170) that goes up fast/easy and protects us from sun and light rain. If we know there is heavy rain in the forecast during any part of our trip we bring our Northern Breeze. This provides shelter from rain, wind, etc.
So, after 2 years of ownership, I still have no regrets on buying our CampInn. It was and still is the best teardrop trailer I have seen. It has the best design I found, the best build quality and great customer service.
As for teardrop camping, it's not for everyone. If I were full timing, I might go with something larger but I have spent 3+ weeks in the trailer and it worked fine the entire time.
Hope that helps.