While an hour and a half is not great, out of the three different manufactures who have announced a backpack PC, MSI currently has the best battery life at an hour and a half.
MSI has stated the unit will use a GTX980 graphics card, meaning this backpack will fit desktop components, which offer better performance over laptop CPU and GPUs. This also means that some components will be able to be swapped out and upgraded, making for a more future proof item.
This is a pretty short battery life, which means very little in a game will be able to be played through completely untethered. Even though this is the highest battery life announced out of similar backpack PCs, it is still quite short.
This is one big caveat, that you can only be mobile and cordless for an hour at a time. Of course batteries can be swapped in and out, but even that could be sen as a pain to do every hour, not to mention expensive in order to own enough spare batteries.
This backpack comes bundled with a wireless mouse, keyboard and display. Including these devices means the PC is all in one, no need to already own or purchase separately other peripherals in order to use it like you would any other PC. This is also good for when the user needs to troubleshoot their VR unit, which will mostly need to be done in programs on the desktop through a normal mouse and keyboard operation, which is included already with this device.
There is a battery in the backpack itself as well as batteries on the belt of the device. The belt batteries can be swapped out when power is getting low without the device shutting down, meaning the player can play as long as they have freshly charged batteries to pop into the belt.
The PC that will be used will have desktop components meaning that the unit will be able to power games better than something using laptop components such as laptop grade CPUs and GPUs. This will of course use more power, but will offer better performance.
This is basically a backpack with a PC and a battery power supply, all inside. What this means though is since this solution uses separate components, they will be easier to upgrade. First the PC will just be one of Zotac's mini PC that is powerful enough to power a ZVR unit. THis in and of itself should mean there are components in that mini PC that can be upgraded or changed. On top of that, the batteries will be a separate part in the backpack, which could also be replaced or changed to an even more powerful pack. Overall, this makes for a more versatile solution due to everything not being all in-one.
Due to the nature of the design, using a backpack and filling it with a mini PC and battery pack, there is potential for this to be a lot bulkier and heavier than the units from HP or MSI, as theirs are more all-in-one, allowing for a more slim device.