Rick Steves is knowledgeable, that much is true, but the way he comes off it's more of his favorites than rather all of Europe; for example Norway isn't the only one who celebrates St. Lucia as Sweden celebrates it just as much based off of other episodes from him and other travelers.
There are other celebrations that are celebrated, from little known ones in Estonia, Romania, Switzerland, etc, to some well known (Carnival, Oktoberfest, Bastille, Feast Days) but [all] are overshadowed by these "well-known ones" in certain cities that have been highlighted instead. If it's a really good one or original, it's understandable to a degree, but sometimes other places in Germany have amazing celebrations for Oktoberfest, or villages celebrating Bastille in France and it would be greatly appreciated as it almost shows that he's found the "best" and not just a tourist spot "original". For example New Orleans is known for Mardi Gras, but so is Mobile, Alabama and needs to be noted for that as well since it was the first organized one.
It's good, but at the same time I have found him to be borderline touristy now compared to his older shows and more so when compared to some of his contemporaries (Joseph Rosendo and Richard Bang primarily).