Some points on the travel scoot:
Light-weight and foldable: It is very light-weight and comes apart easily, and folds very small, so relatively easy to get in and out of the car boot. The main part is about 20 pounds so still fairly heavy, but not too bad if only lifting it in and out of the boot. The seat is very light.
It fits in a very small space (e.g. boot of a Yaris, Micra/March). If I go to a very small crowded cafe (not very often) I sometimes sit in a normal chair and fold it up. It doesn't take up much space if you are staying in the hotel or the like, and it can fit in my flat easily (I don't use it within the flat).
Steps and high-kerbs: This is one of the reasons I got this particular scooter. I live somewhere that had major accessibility issues (improved more recently but still a lot of improvement needed). If I get to a step or a high kerb I can just get off it and roll it up. This is annoying if it needs doing a lot, as it defeats the purpose if I spend too much time upright, but mostly I only get these obstacles now and again (I plan my route for this). I can even roll it up a few steps if necessary (and often I get someone offering to help if it is awkward).
Battery: I got a lithium-ion battery which is a lot more expensive but much lighter, goes longer, and lasts longer (I have 2 batteries. They are 9 years old now and still fine, though I think they go for less time than they would have initially. I don't have to charge up between each outing, though if I have gone much longer than normal I might just in case). You could always buy one with the heavier battery and buy a lithium-ion one later if you can't afford lithium-ion one initially.
Comfort: It is more comfortable than you would think. Your legs are very slightly raised (only very slightly) which is an advantage. The seat is comfortable but the back-rest is not great for sitting in for long-periods. I normally sit on a normal chair if sitting for a long-period, and basically use the scooter mostly to travel around.
Hills: It seems to be fine going up fairly steep inclines, but coming down can be a problem. It is very light-weight, and doesn't have the sort of electric brake some scooters have, so it can roll quickly if the incline is very steep. If a place is very steep I either hang on to a hand-rail with one hand and/or put one of my feet on the ground to slow me down. This is the main disadvantage I think, especially if you lived somewhere very hilly.
Terrain: Obviously it is best on smooth ground (concrete, tarmac, tiles, wood) but can cope with carpet (not sure about deep-pile but it can manage good thick carpets with good underlay in hotels), grass to some extent (it if it was very tall it could be an issue), compacted gravel but it is poor on loose and especially large gravel (also with the older model the gravel can get into a part and damage it. I think this has happened to me recently and I had just replaced this part
It is cheap but annoying to replace. This might
not be an issue with the newer models which don't have an exposed drive-belt). I even drove it in a woodland area once. It had a sort of rough-path done out but still I was surprised it managed.
Reliability: I would say very good. I have had some minor issues which I could sort quickly with instructions. Though it used to be the inventor you were originally dealing with directly, so he might have been better. I haven't had any major issues since he retired (though I lost some screws which had become lose. I hadn't though to check the tightness over the years). I know some of these issues I had have been sorted in newer models (I have one of the earlier models).
Value for money As I mentioned earlier I have this just over 9 years now. Even though it was expensive (my parents bought it for me), it has lasted well and has worked out at a few hundred Euro a year cost, which is money well-spent (and cheaper than all the extra taxis I would have had to get). I think there is a good chance it will last many more years. You can buy replacement parts for all of it as far as I can see. If something goes majorly wrong that I can't fix I might bring it to a mechanic and ask them to have a go (otherwise i have to ship it to Germany).
Effect on my life
It changed my life when I got it. I had not gone down some pedestrianised streets in my town for years until I got this scooter. I was only able to walk very short distances, so was reliant on someone bringing me out in a manual chair for things where I couldn't be dropped at the door and that didn't require much walking (e.g. I could go to a coffee shop and just sit, but not go around a big supermarket or shopping centre). So this scooter has meant that I am much more independent, and basically I can do more things I want to do. I can also get more done when out.
My family could be a bit negative about the wheelchair, but they had a different attitude about the scooter. I think this was partly as it was expensive they wanted to see me using it to get value out of it. They are used to it now and can see all I can do with it (and oddly, now are a bit more positive about the wheelchair when I need to use it - this is rarely, as I much prefer the scooter, mostly on holidays abroad which I have done a few times).
Going out and about is still a lot of effort, and the stimulation, talking, thinking, and prolonged sitting upright is tiring, but the walking and standing for me were the worst part and restricted me a lot, so I manage to cut those out with this.
I have brought it on buses, trams and trains (not a lot though as I don't use public transport a lot).
I have brought it on holidays (within the country I live in). This is great as it gives me some independence on holidays also. For example, on a holiday with my parents, they wanted to visit relatives (that I don't know) that were a bit of a distance away, and I wanted a fairly easy restful day, so they could go off for the day and I could rest in the house, but also go out when I wanted. There was a lovely park and lake very near where we were staying. Having the scooter meant I was not stuck indoors even if I felt like going out, and it means someone doesn't have to be with me all the time.
I am so used to it now I am probably forgetting some of the advantages, as it is normal for me now. I can't scoot long distances, so still need to use other transport to transport me a few miles to get to place. I use it if going shopping or into town, or for days out to places. I learned how to drive since I got it. I don't have to worry too much about where I park, as I can just scoot to wherever I want to get to from the car.
(but should need no car upgrades to transport) 
Also better suited for uneven terrain.
