In using the 5-25 on a couple on other people's guns, my experience is identical to this. Fine at lower mag, love the reticle, but glass at higher mag leaves A LOT to be desired - easily the worst glass I've seen in the price range.
But they are built tough and have good reticles and good turrets, and there are folks using them for ELR with good success, so maybe the glass is more of a personal thing than an actual universal hindrance. One of the ones I looked through is several years old, but the other one was bought about a year ago, so I'm not sure when the "newer" ones start, but if it was before that, then I think they're still grossly overpriced at $1k for the 5-25, especially when you can get something like an SWFA 5-20 HD for the same money, which has fantastic glass. I like the mil-quad, but if SWFA would put an SCR reticle in their 5-20 HD, I'd never need anything else short of a TT 5-25 Gen3XR.