I own both the Celestron 15x70 and 25x70 binoculars. After comparing both here is WHAT I'VE COME UP WITH:

Both binoculars excel and have a clear crisp view. The optics are truly amazing at this price point! I did have to send back a set of the 25x70's due to interior dust being seen as I looked through them, but Amazon sent me a new pair no problem. Both binoculars use the same body. The 25x70's are a touch shorter (1/4 inch) in length due to shortening of the Ocular (eye) to the Objective lens distance. The 25x70's also have a larger Ocular lens due to the increased magnification. Both binoculars need a tripod (especially the 25x70's which are more effected by shaking). GET A 70" or greater TRIPOD! I have a 60" tripod and I'm a short5'5" but when something is near 90 degrees over your head the "60 height of the tripod won't cut it.

I posted an example of the magnification and the Field of View difference between the 15x70 (1st Pic) and the 25x70 (2nd Pic). As you can see the 25x70 gives you a greater MAGNIFICATION but the trade off is the FIELD OF VIEW which is greater with the 15x70's. The actual views through the bino's are sharper as the cellphone doesn't do it justice.

LOOKING AT OBJECTS: In looking a celestial objects the MOON totally fills the frame with the 25x70's. The 4 Galilean moons of JUPITER (yes you can seem) look great in both set of binos. Another thing I love to look at are AIRPLANES. With the use of a tripod I was able to see and follow JETS at 35,000 ft. IT IS A MARVEL! The 25x70's work well here as I can read the writing on the planes.

MY RECOMMENDATION: I would choose the 25x70's. The 25x70's are $3 more so why not go for more magnification. The wider field of view on the 15x70's does allow a better "hand-held" experience but you are still going to need a tripod for celestial viewing no matter which bino's you buy.

ALSO: Both the 25x70 and the 15x70 come with a tripod adapter but I'd upgrade to a METAL one as these binos are heavy. The Barska adapter is metal with a larger rubber tightening screw and is only $8 (see photo). I'd also get some Field Optics Research Binocular EyeShields ($14) to help keep out peripheral light in daytime viewing (see photo).

I originally gave these four stars because the focus has play in it. I bumped them up to 5 stars because of the low price and the fantastic astronomical views. They stay in the focus you put them in, but the play occurs only during adjustment. My 16x50 is much better for daytime sight seeing.

1. The eyepiece lens is 23mm, vs 18mm for my Nikon Aculon 16x50, 16mm for my Celestron 10x50, and 13mm for my Tasco 7x35. Despite this, they have the same eye relief as the smaller binoculars, and also a moderately smaller apparent field of view.
2. I followed the exit pupil, drew a triangle, and quickly and accurately measured the apparent field of view of the Celestron 25x70 to be only 57.5 degrees, and that is the maximum no matter where your eye is. My Nikon's are 61 degrees, my Celestron 10x50 is 60 degrees, and my Tascos are 58 degrees. Visual observation confirms these math measurements.
3. They are noticeably heavier than my other binos, but not a lot.
4. They are easy to hand hold very steady in the day time, without resting my elbows on anything. At night it is much better to have something to brace my elbows on.
5. They look like they are good quality, other than the thin strap.
6. They are 10.4 inches long, and 8 inches wide.
7. There depth of focus is less than that of lower powered binoculars, so I really have to adjust them as I aim around at stuff terrestrially at different distances. These are better for astronomy than for birding. My 10x and lower did not need to be adjusted much unless I looked at something really close. My 16x is in between, but still pretty forgiving.
8. The focus is smooth but has a short lag, and requires diopter adjustment of the right eye to compensate for the lag. In cold weather, the focus wheel is tighter than any of my other binos, but still reasonable enough to turn.
9. I am a bit near sighted, so I get a closer near focus at around 50 or 60 feet instead of the advertised 75 ft. My nikons near focus at 18 ft, not their advertised 28 ft.

As many other reviewers already said, the eyepiece barrels seem too big around, and pinch my nose if I try to get closer to the eyepiece. However, if I carefully measure the interpupilary distance, I can place them so I see the full field of view without the pinch. It just does not come as naturally as with my 10x50. I separated them to see if getting one eye closer would give a bigger field of view, but it did not. I guess how close I get is close enough. It just feels weird them being that far out on my nose and making that third point of contact like that. Edit: next day: I'm getting used to the new feeling.

The correct place to hold these binoculars is by the barrels in front of the prisms. That is how to get steadier views. Better yet, slouch down in a chair and put your elbows on the arm rests. Then all you'll see is your heart beat.

I looked at a distant light, and compared its size to the Nikon's 16x. I find it very believable the Celestrons are 25x.

The field of view is not as wide as advertised. The apparent field of view is 57.4 degrees, not 61. The belt of Orion just barely fits in the view. The moon is 30% of the view. The true field of view is 2.4 degrees, not the advertised 2.7 degrees.

The arms of the eyepiece adjuster also have some wiggle in them causing a 1/4 inch delay when turning the adjuster wheel. I have had to re-adjust the right diopter even when I did not touch the center wheel, indicating it might be moving a bit. But it does not take long to get back into focus. There is also a flare visible off to the side of the exit pupil, though I don't see it during astronomy.

Despite these flaws, I can't subtract a star at only $70 shipped. These binoculars are a league above my 10x50 for astronomical viewing, at least in terms of looking at individual targets. A telescope has many advantages, but these are grab and go. However, to see the phase of Venus, you need to stop down the aperture and sit down to brace your view.
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I easily saw the correct shape of the Orion nebula on a half moon when my 10x50 could see nothing.
I could see the dark side of the half moon, whereas my 10x50 could only see the bright side. My 16x50 also saw the dark side.
Jupiter looks much bigger in the 25x70, but I may need to reduce the aperture to see the stripes. I can see bands on Jupiter 114mm f8 Newtonian telescope at 28x, but I can't see bands at 25x in the binoculars.
The Pleiades look much better in the 25x70 than in the telescope or my other binoculars.
The double cluster in Perseus is clearly visible in the 25x70, and looks tiny with an almost stellar core in my 10x50.
Andromeda, M31, looks better, with M32 and M110 noticeable by it, and very hard to see in my 10x50.
I can see a tiny ring around Saturn at 28x in my telescope, but at 25x, I sometimes see a ring around Saturn and sometimes I don't. On the day that I could see a ring, my 16x50 detected ears.
I can see M13 and other globular clusters as small fuzzy balls. I could find them in my 16x, but smaller. In my 10x, I can locate most of them, but they look like stars. Maybe I can detect a little fuzz on M13. In my 7x, I can't locate most of them, but I can see M13 and maybe a few others, though I don't remember.
All of my observing was hand held, unbraced.
I could point them at whatever I wanted and hit my targets just fine. I had trouble hitting Andromeda right away because I could not see it naked eye.
M82 and M81 are easy to identify in my 25x70 as I sweep over them. I can see the cigar shape of M82 in my 16x50 too, though I can't find either one in my 10x50.
I can see a mountain range on the moon in the 25x70 when my elbows are braced. I've not yet found it in my 16x50.
Airplanes look bigger but take longer to find in my 25x70.
At 25x, you can't tell where you are in the sky from the star orientations. You just have to point and look, and you know where you are when you see the object you are looking for. At 16x, I can pan around from bright star to bright star and figure out where I am by memory. At 10x, I can see some bright stars in the same field of view, but have to pan for others. And at 7x, you can easily see where you are.
I actually think my view of M31 was more enjoyable in a 15x70 than in these 25x70, though I know the Orion nebula is better at 25x. It keeps getter better even at 60x.
M33 can be located at lower power, but the 25x70 gave the best view, giving maybe a hint of spiral structure.