I loved the original Transformers series. While it had its flaws I still found it extremely enjoyable, and was terribly upset when it ended. I was happy when they decided to continue it with Beast Wars, although admittedly that got some getting used to, with the CGI and the fact that everyone had a beast form as opposed to the mechanical forms I was used to. But I got past that and really came to love that show as well. Then came Beast Machines, a show with limitless promise that simply failed to deliver. I thought that with Megatron's machines vs the Maximal beasts there might finally be the mix that I always enjoyed in G1. But then Megatron only made three different molds. And Megatron himself, who had a great transformation, rarely transformed at all. I hoped that there might be some true Vehicon combiners, in the vein of Devastator or Menasor, but that wasn't to happen. I could accept some of the new forms of the Maximals, but Rattrap wound up looking ridiculous and Botanica had to have the worst alt-mode ever. They completely misinterpreted the Key to Vector Sigma and should have found some way to incorporate some G1 characters into the mix. They also became almost cult-like with the whole "organics are good" mentality. Having the series end with Cybertron being turned into an organic paradise made little sense to me, and really didn't give the great G1 storyline a worthy ending.
Plus the fact that Megatron simply went back in time again and won the Beast Wars by himself pretty much rendered the entire 3-season run of Beast Wars meaningless.
Very, very disappointing end. Left so many questions unanswered in the G1 universe, and at the same time left me not wanting a sequel.