Most of my favorite shonen have a slow start and build up to better episodes.....Gintama, HxH, FMA Brotherhood.
I guess I can understand not getting into it on Toonami with just one episode a week but that's why I prefer to marathon anime.
A slow pace isn't a valid criticism of a show, bad pacing is uneven pacing and with all the shonen out there with uneven pacing riddled with filler and dips in animation quality I find it bizarre to see people complaining about Hunter x Hunter so much on this site.
There are plenty of terrific shows out there that are slow burners like Mushishi and Moribito that seem to get overlooked by some and I can only see it as a product of a "instant gratifcation" mindset