Holding looks very good. Already good enough to compete for the first eleven. A superb buy and proof that we still have the scouts to find good players who are cheap.
Xhaka is also very pleasing. I love the way he sprays the ball around but so crisply. He's a player we have needed for several seasons since Arteta's injuries caught up with him.
Mustafi - well we have no idea yet. For the price we paid, I hope he is worth it and equally importantly, can form a viable partnership with Koscielny. Mertesacker may be captain but he'll likely by 3rd choice when he returns next year.
With the above players hopefully we can seriously tighten the defence.
Perez is an interesting one. My guess is he did indeed pursue multiple other targets, including Lacazette. Lyons clearly asked in excess of £50m for him and Wenger decided it wasn't worth the risk. Perez is cheap so even if he is only a one or two season stop gap solution, it doesn't matter. We still have powder to burn next summer for the world class striker.
These do seem in short supply at the moment, and reluctant to come to the UK. I'm sure Chelsea and United would have been in for Higuain, for example, had he shown any interest in playing in the EPL.
What will constitute a successful season for me? Finishing close to 80 points and at least second. That means we'll have beaten one of Mourinho or Guardiola.
It would be really nice if we could get at least one round further in the Champions League, too.