Recently upgraded my fritzbox 7490 to a 7590.

We have a lot of devices on the network, use the 7490 vpn server, port forwards (and Upnp), parental controls, and myfritz for dynamic dns. 

7490 was released in 2013, so is really old, VPN was slow and unreliable.  Web interface was slow and buggy. eg, the network devices page could take 1 - 2 minutes to load, and the parental controls page would randomly load only half the page. 

So, I upgraded to the 7590 ...  huge improvement, vpn works properly, gui is quick (network page load time dropped from 2 minutes to 4 seconds), parental controls working.    I don't have measurements, but I feel the internet is snappier when multiple devices are concurrently active, ie, one device consuming a large chunk of bandwidth doesn't affect the other devices so much. 

Definitely recommend the upgrade if you can find a cheapy on trademe.