I have a bit of a disdain for alicorns that are not significantly larger than regular ponies, so I prefer her as a unicorn. It just makes her seem a little bit more relatable, and fits in much better with the race dynamic of the Mane Six. (Two unicorns, two pegasi, two earth ponies) The balance has been skewed off now and it bothers me because of OCD nitpickyness. Also, the way it was done too quickly and poorly in the episode it was done has kind of tainted it a bit for me. I just really have trouble believing she earned it due to the episode being so rushed, and I can't quite get over that.
Also, they seem to mostly have her act as a regular pony rather than a princess, not showing many plots about what being royalty must be like and how the change has affected her. She's not the same anymore, and whilst I would've preferred they save alicornhood for the last episode of the series, they could at least handle things a little more appropriately. Honestly, I find it worse to treat things like the same old when they are clearly quite different. The addition of wings may be minor aesthetically to most people (not to me though - if you add even one detail like that to a simple design like a pony's, it changes it significantly), but in what it means within Equestria, it is very major. She is now a member of royalty, somebody of important status. It should have changed a lot of things. I don't mind change if it is handled properly, but I really don't think her alicornhood has been at all due to the nature of the show. They really can't go into that sort of detail due to being slice of life, although I also understand that the change was controlled by toy mandates likely, so it isn't their fault as much. However, I prefer unicorn Twilight for that reason as well. Because with her, it makes sense to just act like a regular old unicorn.