Yeah, I think our deck-building experience definitely colored our experience. Two of my favorite things about Dominion are how quick it is and the choices you have to make. The turns in paperback are definitely slower, and that was frustrating.
The difficult choices were in actually creating a word as long as possible, and less so in which letters to buy at the end of the turn. So it's definitely very Scrabblesque in the sense that the turns are puzzling your best option on which word to play -- and there are certain interesting elements, such as getting bonuses for using more wilds, and I'm sure several others that we didn't get a chance to see. I'm definitely a scrabble fan (although I rarely play it), and that part of the game could be okay, although I think I'd rather just play Scrabble than Paperback.
I think that the most frustrating part was the abundance of wilds overall. The tiles you have in Scrabble really limits your options -- while there's potentially many places on the board to go, you are fairly limited by your tiles, and they really guide your choices (apart from the 2-3 letter short words, which adds a whole new dynamic that isn't present in Paperback. Longer is always better in Paperback, I believe.) In this game, you can be sitting there with 7 letters to build from, 4 of which are wild, and rather than this being liberating, it was extremely overwhelming to me. It gave me the sense that "I have four wilds, of course I can build a seven letter word!", but being unable to find that word quickly was frustrating, both for me and for my opponent. A time limit is definitely an option, although it's not going to make me feel any better when I'm unable to use all my letters. I imagine this gets better later in the game as more and more letters are added, and the wilds are less frequent. (However, the VP cards count as wilds, although they don't add any money for buys that turn). I definitely do want to play it again, and hopefully get through the entire thing.
I think the game attempted to combine the best parts of a deckbuilder like Dominion and a word game like Scrabble. Unfortunately, the parts don't combine that well. A lot of the appeal from Dominion, to me, comes from not just playing your deck, but choosing what to put into your deck, and it's just not interesting in Paperback, unfortunately.
EDIT: Looking around, it's getting mostly positive reviews from what I can see. So maybe it's just not my cup of tea. I think if you're looking to Dominion as your point of comparison, you won't be that impressed -- if you're looking to compare it to Scrabble, it can do well.