I actually have this tank, it is a little over a gallon but after decor, filter and heater it is about a gallon. I have mine heavily planted with Hornwort, wysteria, moss ball and vals. Because of the plants, and bio filter I only have to do 1-2 25-50% weekly water changes. It is still a lot of up keep in comparison to a 2-3 gallon tank with the same amount of stuff.
I have also made a lot of mods.. the handles I have sealed off because if you keep the tank full it you could easily have a jumper, made a plexi lid which helps stop water evaporation and keeps the GS from jumping. Here are some pictures of my set up..
In the end though, I do like the tank. The windows are really the best feature because the betta actually plays in the windows, as you can see from the pictures. It is compact so it fits on my desk perfectly.
However, if you cannot do the proper water changes I would not recommend this tank. Since, it is small the water can become toxic fast if one water change is missed you will have an unhappy/sick/dead fish. Also keep in mind that you are just buying the tank and need to also purchase all the extras you would need. There are other bigger tanks that come with heater, filter, light, ect so in the long run it is cheaper to buy that then buy piece by piece with the Umbra...