I've only been playing a couple weeks or so, but I'm fine with the setup. Technically it is a little p2w, but only in the sense that any CCG is going to be because nobody starts with all the cards. If that's a problem for someone, they should probably find a new genre to play.
I did feel a little underpowered in my first few games, but that wasn't due to a lack of legendaries. If anything it was a lack of the more useful commons that hurt, but that's going away quickly. Even then, I still manage to win a lot of my games(outside of Arena, I die there miserably).
The thing that surprised me is that unless you're trying to build a deck quickly, you can earn packs at a very generous rate. Suppose on an average day you do one daily for 40, and get 3 wins, most likely in the process. That's 50 gold, which is enough for a pack of cards every other day for playing very little.
Right now I'm not spending too much time on the game. I do my dailies when my log is full, and on the weekends I go to the arena to die and get packs. I may not be progressing quickly, but it doesn't feel like a grind at all.