I don't have one, but, you're still looking at some added costs to it, even if billed as an all-in-one.
First, the lighting is not 110W of T5, it's 110W of T5 CF bulbs (CF with a little smaller diameter, not to be compared with how you would normally think of T5 lighting). It's enough light for most things, but if you're thinking of high light requiring inhabitants, you may need to mod in additional lighting.
Second, the included skimmer is from the same folks who gave us the prizm skimmer, which is not on anyone's top 10 list to my knowledge. Now, Red Sea does claim the build in different on this skimmer, but it looks very similar, and I haven't read enough from users to determine if it's good or bad. Should it be bad, add in the cost for a new skimmer.
Third, you can reconfigure the rear chambers, but you will decide whether to use or toss their skimmer should you wish to have a built in refugium. It's possible to use the cutouts on the rear hood they have in place for plumbing in a chiller as a way to add a separate refugium, but that's beginning to defeat the all-in-one premise.
Finally, having one electrical plug is a big plus. However, the built in timer is pretty basic and is not going to let you set any complicated dawn/twilight sequences. This may or may not be important to you, but I find myself with timers coming out of my ears for different light modes (I really need an RK II).
There's no doubt it's a set it and forget it turnkey solution, especially if you can live with the lighting as is. But, for over $600, I think you would find better buys out there that can be set up to your personal taste. Before you decide, take a look at the tanks at cadlights.com. They're making some beautiful nanos', and give you many options to set it up for your particular needs. This is not to bash the Max, especially as I can't give you first hand experience with it, but judging from what I've seen in the nano market, I would comparison shop before pulling out the credit card.
Hope this helps.
Henry