All the tubes are interconnected which means lots of joints and valves. Therefore many more possible leak points.
It also means each tube is unique in its position in the tent and where the connecting joints are. You can't just buy 1 spare airbeam like you can in a multi point system, you would have to buy a full set.
On the plus side, single point will have bracing beams front to back, which makes for a solid frame
120th night in our one-point inflatable as I type this and no problem with the joints or valves (touch wood) but . . . .
Cheap ones or mainstream pre-2016 models will probably have a woven PE sleeve over the inner tube which is weakened by stitching. In hot weather the one-point jobbies can be prone to splitting round the interconnecting valves, which will lead to a blow out if you don't deal with it.
You can pre-empt the problem by taping round the weak points, or chuck some money at a good, new tent - or enjoy the Sword-of-Damocles thrill. Here's a post I did last year (35 tent-nights ago) about what happened to us: link.
You're unlikely to be able to get a full set of replacement beams once the tent's out of warranty (but you could get a matching awning / extension / 2nd hander off E-Bay and use the tubes).
Despite all that, our next tent will definitely be a single point inflatable. As per Jim's comments above, they are brilliant in the wind, super quick to pitch, and pitch well because they find their own shape with very little encouragement.