I have a Bissell and I'm not too happy with it. I recently got a Hoover Steamvac V2 and it's quite a bit better. The Bissell I had only had a straight stationary brush, while this Hoover has several rotating brushes. I also had a very disappointing Bissell upright vacuum cleaner for a while, so I'm pretty well soured on the brand.
Neither shampooer has done well on small spots (e.g. coffee) for me. I found that Oxy-Clean really worked like on TV for these. Even with the better Hoover machine, I had to go over bad traffic areas many times to achieve a satisfactory result on my light-colored carpet.
I have the bissell pro-heat pro-tech upright steam cleaner and I'm quite happy with it. I had stains on my carpet from baby formula when my son was a baby, raw hide from my dog, and just general dirt/mud stains from when my lunatic dog goes charging around the house after digging in the mud. All the stains came out. Some took a few extra passes. You just have to buy the pre-stain formula in addition to the regular carpet cleaning solution. I think the model I got was one of the top models, but it was worth it compared to renting a machine. Plus other family members have gotten use out of it as well.
Steam vacs are on my list of "things that it's better to know someone who owns one than to own one yourself", along with boats and swimming pools.
Having said that, I borrowed the Hoover steam vac recently from a brother-in-law and it did a marvelous job getting the carpet clean in the nursery I'm putting together. I didn't think the carpet was too bad, but I was stunned at the black gunk that came out of that steam vac when I was done. And walking on the cleaned carpet the next day with bare feet testified to the suction power--the carpet felt a half-inch thicker because the fibers were standing upright.
I was just thinking about starting a thread on this as we are in the market for one. That V2 looks like a top pic. For the small stuff, we use Folex. This stuff leaves no stain behind. Great stain remover and can be bought at any Home Depot.