This is actually a great question, and one that's a lot closer than folks may think. I really didn't like hearing that SF got Boldin for a 6th. That's ridiculously cheap, especially when compared to what we paid for Harvin. Just on a picks for picks basis, we gave up a ton more.
Yes, we got a ton more in return, as we should have. And I think the Harvin move was spectacular for us. I think we got the better side of that deal, too, even giving up a first plus for him. He'll be with us for a good several-year window, and he's one of the best in the game right now. That move was the perfect one, and came at the perfect time - much better than if we'd have sprung for a marquee receiver last year.
That said, SF's a bit more stacked than we are. They went further in the playoffs than we did. They did accomplish more, as painful as it is to say. It's fact. They're missing very little, and to pick up a guy like Boldin might just have been what they needed to take them to their next Super Bowl win. I think he's better than many are saying. I see a lot of sour grapes from Seahawks fans regarding him - "Eh, he's not really that good anyway. Too old. Done already. Etc." But the fact is, he's a very solid receiver, and that's one key cog that the 49ers needed. To get that cog for a mere 6th rounder is absolutely phenomenal for them.
I think the whole thing is a push. We got the better player, but we sacrificed more for him. They got the better deal if taken straight up, but as they were gunning for Harvin as well, it evens things out. If Harvin were to have gone to them, it would have been very bad for the Seahawks, and that alone makes getting him worth a little more in cost. The fact they got Boldin evens things up for them.
One thing is for sure: the NFC West is going to be VERY COMPETITIVE next year. And VERY TOUGH to beat.