I'm sorry you had that experience. In reality, I think it varies from person to person. I have Premium, so no ads, but I had the regular version for 2.5 years previously and never noticed it being balky or slow.
Some browsers are better than others...Firefox is the best, I think; IE not so much. Others have complained about problems with the site loading also; you're not alone, but most are using it without this issue, so I don't think bait and switch is a fair assumption.
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days