I bought a Kobo Libra H2O a while ago. I'm quite pleased with it. I personally would have preferred a Sony PRS-505 with a higher resolution screen, and maybe a red backlight - but I'll make do with what's on the market.
Here's the good and the bad points of the Libra H2O from Kobo.
It's comfortable to hold and comes with physical buttons for turning pages. I had a Kobo Somthing-or-other many years ago that didn't do that, and it was annoying. I'm quite slovenly when it comes to reading in bed, and will often read on my side - so the auto-rotate feature working so well is very welcome (and arguably necessary, given the asymmetric form factor).
The backlight does the day/night-time thing where it gets progressively redder as evening approaches. I like the feature, but wish it got much closer to a red light. As it stands it gets through to a orange-ish hue, and no further.
It uses USB for file transfer. Thankfully Kobo haven't went insane and decided to enforce managing stuff through their website or store. You do get a simple mass storage device, and you can let Calibre manage it.
Kobo also sell a sleep cover for it, which is great. They're useful.
The Kobo Libra H2O isn't user-friendly. You're expected to either sign up for an account to use it (how else can they sell you books?), or instead set it up using their proptietary software.
You can get around this quite easily, provided you're technically minded. Connect your Kobo to your computer and insert a dummy user into the user table within the sqlite database file. Your query (and the data) will be something like this:
INSERT INTO 'user' (UserID, UserKey, UserDisplayName, UserEmail) VALUES (3, '', 'Example', 'email@example.com');
By playing around in sqlite, you can also get rid of the recommendations that Kobo load onto the homescreen. These are just adverts that take you off to the Kobo Store (which wont work because you've never connected it to wifi), so they're thoroughly annoying.
You're stuck with the storage your device comes with. It doesn't take an SD. How we went backwards on that front, I don't know. Kobo doesn't even sell variants with different storage configurations.
I still don't think the UI is great. On the PRS-505 you had a series of buttons down the side of the screen, which were used to (for example) navigate to books starting with the letter L, M or N. It was very quick, it was very easy, anthere was minimal glamour to it. Kobo however is slower, wants you to see the covers of the books you're passing by, and the touch screen is far less precise and responsive.
It isn't at all repairable. Before you can replace the battery, you need to get into the thing, and Kobo do not want you doing that. Nor do they want you getting your hands on parts. The Kobo Libra H2O is a device intended to be replaced when it fails. Which is a really, really shitty and unsurprising thing to see Kobo do. They have, after all, re-released largely identical e-readers for the last decade, with minimal innovation.
It's alright. It tries to push you towards Kobo's account and online shite, but you can get around it with some minor work. The hardware is nice, but you're never going to be able to repair it, and storage expansion is out of the question.
Personally, I'd really like to try putting together an OpenBook. Although I don't have the kit for surface mount components any more. So that'd have to come first.