Pros: This entry-level Bissell carpet cleaner is actually better.
Cons: Smaller tank, so you have to fill it a bit more often.
I had the big-full feature Bissell 7920 carpet cleaner for five years; I managed to crack the front suction plate area by being a bit too rough with it, but part of this was due to how heavy the full-sized until was: 35 pounds; add five more pounds when the 1-gallon water tank is full. It was a handful even for me, a big, 6-ft tall guy.
So I decided to replace it with the smaller Bissell 25A3. I love it. It's ten pounds lighter, and that makes a surprisingly big difference. Yes, the water tank is 0.75 gallons instead of 1 gallon, but I don't find the smaller tank to be a problem. Also, I like the 2-in-1 combined system, where you add the cleaning solution to the water tank, using the built into the tank top measuring cup; works great.
The 25A3 only has just one attachment for the hose, instead of the multiple attachments for the 7920. But guess what: I hardly ever ended up using those attachments. It turns out that all of the 7920 attachments fit the 25A3, though; so I kept those attachments in case I ever need them.
The smaller size makes the 25A3 easier to store in my closet. It has the identical 700-watt heater element as the 7920, so you're not scrimping there. This also means that the 25A3 is no more, and no less, prone to having debris or hard water deposits build up inside the water channels of the heating element, and eventually block the water flow. But it turns out that it's not too hard to access the heater element in the top portion of the Bissell, clean it out, and re-install, in which case you're back in business at zero repair cost.
It is much easier to clean the front bezel when you're done with a cleaning session: The bezel pops off using a spring-loaded fitting, and goes back together just as easily and quickly. The 7920 required removing two screws and fighting a snap fit, always a bit of a pain. This feature alone makes the 25A3 superior to the full-sized Bissel carpet cleaners as far as I am concerned.
The cleaning ability of my replacement 25A3 is every bit as good as the full-sized 7920, and the 25A3 costs about 60% of what the full bells-and-whistles 7920 cost. Only if you have acres of carpeting would I say that the 25A3 is at a disadvantage to the 7920.