Don't bother with them if you are pretty lax about watering and plant upkeep. With the plant inverted, it will go through a lot more water than usual and are more susceptible to the root ball drying out and shrinking due to greater exposure to hot/cold temps. Also, if the plant is not fertilized properly, it wont develop a strong enough root system and when it starts to bear tomatoes, the plant will break off.
I have a landscape/garden business and have had a number of people buy these things then have their tomato plants die, and then b*tch to me about it until I convince them to put in a proper garden. If you are adamant on building these things, go for it, though you may want to plant a smaller variety like roma/plum/cherry tomatoes as these will be easier to maintain. Though, you can always put them in hanging terracotta pots, which will do well if in good sunlight.
Grape tomatoes in 5 gal Homer Buckets from HD. Great for everything. WE are trying Habaneros and Ghost chillies in them this year. Jalapenos were great last year. Not a whole lot of yard, but plenty of trellis.
Reviving this thread based on my experience of trying this. I got one free from my mother and bought another (different brand) from Home Depot.
I knew they would take more watering but had no idea of how much. I live in central Texas and we are already in the triple digits of dry, hot breeze daily. I had tried twice a day with a drip system - soaking twice a day and that worked for a while but when the plants got bigger and the temp rose by 10 degrees, I would find them wilting by the end of the day. Now I am drip watering 3 times a day and it seems ok.
I suspect that in a more humid and less windy environment these might work better. Also, I think next year if I do it again, I will plant cherry tomatoes in these and my better boys on the ground in cages.
However, the jury is still out. I have a lot of green tomatoes on the vines and because I have an automatic drip system, it may work out well.
Might be convenient if you live in an appartment and want one or two plants. I doubt the plants would yield more or anything as that stupid commercial suggests. I hear plants in those things were susceptible to rot, as water drips on the stem.
Do all these products have an air permeable "pot"? That could be why you need more watering, you are likely losing more to evaporation.