I moved into my house in Jan, 2010.  It's a two story with tile and laminate on the first floor and carpet on the second floor and on the stairs.  I didn't have a decent vac and so I purchased a Dyson airmuscle.  I had used my granddaughter's Dyson and was impressed with it.  It didn't take long to realize I was not going to be hauling it up and down the stairs all time (I was 66 at the time).  So I got a Dirt Devil canister for the downstairs.  Don't ask my why - I really prefer uprights - but for some reason the Dirt Devil appealed.  For maybe a month.  Then I realized it was really doing a poor job.  I continued to use it for awhile however, as how many vacuums can you buy within a couple of months?  I did, after awhile, purchase a Shark Navigator Lift Away to use downstairs on the hard floors and the two area rugs.  I also used it on the stairs and was impressed how much easier it was to use and how much pet hair it picked up.  (2 dogs and 1 cat, all shedders, makes vacuuming frequently necessary).  After about a year, as I was vacuuming the upstairs with the Dyson, I noticed it was leaving a LOT of pet hair behind.  So I took it all apart to see if something was jamming it - nothing.  Checked all the filters - they were fine.  So I went downstairs and got the Shark.  I started with a clean dust bin and had to empty it twice before I was done.  Over the past several years I have tried this again, with the same results.  The Dyson simply is not doing the job.

Some things I like about the Dyson:

• The long cord. 
• The ease of emptying the dust bin.
• I like the long attachment tube - it makes it fairly easy to reach high areas as well as using it on the stairs.

Things I dislike about the Dyson:

• It's too heavy.
• I can't say it losing suction, but it certainly isn't picking up all the animal hair.
• The stair attachment is way too narrow.  Plus it's not especially effective with pet hair.

Things I like about the Shark:

• It's very lightweight.
• The lift away feature is perfect for stairs and high ledges.
• It is great at picking up pet hair.

Things I dislike about the Shark:

• It tips over too easily (a drawback of it being so lightweight).
• The cord is too short.
• The stair attachment is too narrow.

 I'm looking forward to the day I can ditch the Dyson and purchase a second Shark.