Don't get your hopes up for pre-WC signings IMO.
Martinez can partner both Ramsey and Arteta (who will continue to be an important contributor for us - he's a good player!) and can cover at CB. £30m is steep for a holding mid, and he could be a bit more mobile and better on the ball, but he obviously has a lot of very good qualities. I'd be very happy with his signing.
I'm hoping Wenger is a little less concerned about price now and will merely be annoyingly picky about the players he wants. £42.5m for Özil was hardly a bargain - it was the right player at a reasonable price. Hopefully we see the same with a player of Martinez's quality.