TL;DR : I don't like the first game. The rest is awesome.
Long before I started playing Black Mirror, I already had played Black Mirror II and I absolutely loved it. I couldn't wait until BMIII came out. That game too satisfied my needs. When I saw that the trilogy was finally coming to steam, I insta-bought the first game too.
Although I have only played for 15 minutes or so, I already felt like the game wasn't as good as the rest of the trilogy.
I first of all had difficulties getting it to start up and when I was finally playing the low quality really bothered me. And I'm not just talking about graphics; Whenever I start a conversation I takes the npc waaay too long to respond, because it first has to complete their (really laggy) animation. I also didn't like the characters to all be so uptight. Of course, that's because the setting is in a old victorian castle and all the characters are rich. Nothing to do about that, but it's just not the same to play as Samuel as it is the play Darren(main character of BMII & III).
I can safely say that the studio really did improve the game quite a bit with BMII and III. Of course, going backwards to the first game, I couldn't expect much, but I did. And that's why I'm a bit disappointed; because I wanted more of the same. The game's probably pretty good qua story. I just don't seem to have the patience. I'm ready to move on.