I am surprised Shadowmere was not a thing with the Dark Brotherhood content, given Zenimax's absolute disregard for ingame sensibility and restraint when we all ride sparkly coloured camels, wolves, bears and are being followed by a bunch of silly Pokemon pets. All for the greater good of money. So, the exclusion of Shadowmere as a purchasable mount is a great surprise.
i think the camels, bears, guar, and kagouti are meh. I couldve lived without seeing those. They're all awkward mounts, and its funny to see them hobble along especially when the rider has max stats. just looks goofy.
I liked the wolf mount, i liked the lion mount, better than the above. I would like to see shadowmere though. That would be a good addition. I thought they were going to have halloween mounts/pets?