The Tiamat campaign was the first one they printed, it was a “launch title”, and they hadn’t really found their groove yet. I’ve purchased most of the hard cover modules for 5e and I have to say they keep getting better. They’ve found a sweet spot of interesting tactical situations, which is the bread and butter of D&D, and great world building that really lets the players integrate, make their own story, and shine.
Your results may vary, a bad group or DM will make any game shit just like a good group makes any game better. 5e really gives you the tools you need to run the kind of game you want. Focus on the dungeons, or meander off into interesting story sessions… or both!