Hootman does point out a few issues that nids had/have and how the edition swap helped/hurt. I have a very active nid player in my meta and he tends to do well. For reference I have a very marine heavy meta with a few eldar/dark eldar players, the IG players who recently left, 3 necron players, and my Tau.

He uses Yrmgarl genestealers to good effect as well as a swarmlord, 2 trygons and a tervigon in addition to his 2 big broods of gaunts (one of each type). The MCs were good anti-vehicle with rear shots and 2d6+str vs. vehicles with the MCs in 5th helped a LOT in cracking stuff. His Yrmgarl were good against infantry with their morphing/rending and the gaunts could shoot out termies with volume fire or just tie up a nasty unit if he needed to.

Several parts of that have changed in 6th (notably the 2d6+str to pen) but MCs are still amazing at killing terminators and can hit vehicles MUCH more reliably with str 10. Gaunts and genestealers can still do their job and they have access to some VERY nice psychic powers across a LOT of their units.

Nids have a fair number of issues but they are not "unplayably horrible", that is a distinction that I don't think exists in the game really (barring the rages when our deathwing player stomps me and makes me cuss the new wound allocation rules by running melta AROUND my shield drones on my suit teams). I do believe that they should be on the list to be given a new codex but chaos, Tau, and Eldar should be addressed first for their much greater difficulties in the current edition and metagame.