I have the 5mm, 13mm, and 24mm.  I like them very much and use them more than any of my other eyepieces .  Just one man's opinion.

I'm very happy with my 17mm and it has been my main eyepieces, granted, I don't have many eyepieces to choose from. I liked it enough to pick up a 5mm recently but I haven't had a chance to use it yet. They are very comfortable and easy to use.

I have the 17 and 21mm, and really like them, especially for DSO work; for the money, you can't go wrong.  If you're looking for a smaller focal length EP for planetary work, you might check out the TMB/Burgess Planetary line.  I've got the 8mm that I use for planetary work; I found the 68 degree AFOV of the Hyperions to be a little too big for planetary work, but that's just my preference.

 I purchased the 8mm and the 13mm Hyperions at NEAF last weekend.  Tuesday night was clear-ish and I was eager to test them out (from my heavily light polluted back yard in NYC).  The showed a remarkable improvement over the plossl set that I purchased with my Nexstar 6SE, and so far I am very pleased with them.  Very flat field and the 68 degree AFOV is truly stunning!  I imagine that there are eyepieces that for 2-4 times the cost (or more!) that would show a small improvement in my scope, but these eyepieces are vastly superior to what I have been using, especially for their price point.  Workmanship is excellent, they are not as physically heavy as some of the other eyepieces I was comparing and I look forward to using all the features over time.  After I make it to some dark(er) sky parties this summer I will be able to fully assess all the features of these eyepieces.  I think I see the 17mm and 21mm Hyperions in my future as well for DSO observing, with the smaller apertures not really appropriate for my smaller scope. 

David Shepherd

Celestron Nexstar 6SE