Well, like it or not, Pachter is a very, very well respected source, even if people on GAF laugh at him constantly. There's a reason he's in the position of power he's in. So there's that. Secondly, I have also played the WiiU, and his points are accurate. The Wii Pad feels kinda like a toy (not that it's a bad thing) and it should be multitouch capable. People expect that at this point, especially in an age of iPhone.
I've read the article now, and he was slamming them for sure. However, he was slamming them for completely real, legitimate reasons. He was slamming Nintendo for being Nintendo, and that's fair. Nintendo's E3 conference was disappointing. Saying "...most reveals fell flat. In fairness, top-tier announcements like New Super Mario Bros. U and a Shigeru Miyamotointroduced Pikmin 3 were nice surprises. Regardless, when Team EGM left the Nokia Theater, the consensus was disappointment." Sounds fair to me. Even if you go back to the E3 press conference thread, people were like "ZOMFG WTF NINTENDO LAND?!!??!" It was a pretty disappointing press conference, and Nintendo hasn't done much to sell the system afterwards. It is harsh, but is in no way shape or form close to an "embittered fanboy blog entry." It reads like someone who was disappointed in the showing, and states that Nintendo still has ground to make up in order to really convince the majority of people that the system is worth buying. I agree with this.