The Europeans call this style the Bungalow Tent and that sums it up nicely really, they developed in Europe in the 1950s as more people were using tents for leisure and demanded more space and comfort

Broadly they consist of a framework that has relatively flat roof with near vertical poles at the corners and sometimes along the walls too
Good points
Very good useable space created by the high walls, they really can be like little bungalows
Pretty strong, not so much by design but by construction, the strong steel frame and tough Canvas make for a comfortable place to be in a storm
Can have huge living spaces with nice bright windows and nice curtains, so you could spend long periods "enjoying" the English weather
A lot of models came with a "kitchen extension" (a space with vertical canvas wall to set up you camp kitchen), this can be very useful when laying out your kit in the tent
Incredible bargains to be had second hand, if someone tries their new Frametent and has a nightmare putting it up then it will be on Ebay for next to nothing and still have that lovely new Canvas smell . . .

Possible concerns
Not so easy to put up as the brochure might claim, with skill and practice you should avoid divorce court. A tough solo pitch for any but the smallest models
Weighty and bulky. A wet canvas from a 6 berth might weight 30 to 40kg, the frame 20 to 30kg - you will need a big boot on your car for one of the bigger models (which is one reason trailer tents were invented)
Weightly and bulky - a tent you will have to clean, dry and pack away at home, so if you live in a studio apartment it will be fun to care for it properly
Limited to 6 or maybe 8 berth - in these times of 12 berth tents they can actually seem quite small, but if you have an above average number of kids or want an extended family in one tent then it isnt likely to work out

Which makes?
On the used market you will find almost every brand of tent made Frametents, they were hugely popular and there are plenty to choose from. In terms of the mainstram brands Cabanon is often the benchmark in the UK for good quality. Relum are pretty good too.
Which Models?
Each brand had its own model names for now we will focus on the Cabanon range, if you like a shape or style it is a fair bet plenty of other brands offer something similar
The smallest variants have a flat sloping roof and uprights at each corner, like the (very cute) Cabanon Calais or the Etna shown here
The larger variants have a semi ridged roof (running either length-ways or width-ways) and 6 or 8 sets of 'legs' to create a robust and spacious tent. Pretty much any frame tent you see will fit this sort of description

The Antigua was a typical Cabanon Frametent with lengthways ridge and relatively small living area. You can see the zip in panel on the side that allows expansion by adding an extra utility space or bedroom

The Aruba model offers rather more more living space from a similar layout. This picture also shows the typical accessories avaialble (which can now be worth as much as the tent alone)

About the largest design was the Cabanon Espace, with room for 8 people to sleep and dine in comfort (if you believe the marketing bumph)