I like it! I am a fledgling astronomer, so my input is questionable, but I like big optics, so for the money ES rocks.
Used on a 15” f/4.5 obsession the entire moon was visible through the eyepiece. The details were outstanding from the center to the very outside edge. Oh yes the Orion Nebula wow. Thanks opt for your recommendation.
I don't have a ton of eyepieces but I have observed with some of the best mass production eyepieces there are. This was my first step into the world of $100+ eyepieces and it was a great choice. The FoV, eye relief and edge to edge sharpness is fantastic. Many in my astronomy club have complimented it as well. I'm going to get the 20mm next, this eyepiece has sold me on sticking with Explore Scientific.
It really is comparable to the Ethos line. The only downside is the weight of the EP. It is significantly heavier. Under challenging conditions for an EP (F4.5 and lower) it performs as well as the Ethos. Using a coma corrector, the 14mm ES 100 is very sharp at the edge of field in my 16" F4.5 Dob. It may even be better than my astronomy club's Ethos 13mm. Without a coma corrector it is ok at the edge.
This eyepiece is a real winner. Excellent sharpness & contrast. Comfortable to use. Edge performance is very good in my f/4.5 Newts (without a coma corrector. The 100 deg field, while not quite perfect at the very edge, really makes you feel like you're there. I'm hooked, and will be getting the 9mm ES 100 deg as soon as I can get the funding in place. There are exactly 4 potential downsides that I can see to this eyepiece: 1 price (which is actually relatively low compared to a similar Ethos, 2 size/weight, 3 eyeglass compatibility (I would only see ~75 degrees with my glasses on, but fortunately my astigmatism is mild enough that I don't need to wear them with the 14mm like I do with my 30mm eyepieces, and 4 after using these, your 80 degree eyepieces that used to seem so amazingly wide will now seem claustrophobic by comparison.
I started with the 14mm eyepiece, and love the 9mm too. With my next pay check I will complete the set (20mm. Observing is great when three eyepieces cover 90% of your needs. The view through my 16 Dob is awesome.