Essentially, here’s the criteria I would use to judge things – if your site is made up of primarily static, HTML-based content, then you probably don’t need a VPS package.  However, if you have a large amount of files stored, multiple sites, dynamic content, and the possibility of major traffic from time to time, then you might consider upgrading to a VPS. It’s a powerful package that allows you to do more than you could with a shared hosting plan, but requires less investment than a dedicated server.
InMotion VPS hosting offers a managed server with a management and security update plan, so business owners can concentrate on the business itself, and leave the complicated matter of site management to InMotion’s team of experts. This is generally a more popular option instead of self hosting, as the majority of business owners are not computer experts, and don’t have a dedicated website manager on staff.
While using a shared hosting server, you do not have access to the entire server, unlike in a VPS, where the entire virtual server is under your complete control. Hence, either you or someone you employ will have to look after the server and ensure that its performance remains optimum. If your VPS provider takes charge of maintaining the server, it is known as a managed server. On the other hand, in an unmanaged VPS, the entire responsibility of the server will rest on your shoulders.

Unmetered hosting is generally offered with no limit on the amount of data-transferred on a fixed bandwidth line. Usually, unmetered hosting is offered with 10 Mbit/s, 100 Mbit/s or 1000 Mbit/s (with some as high as 10Gbit/s). This means that the customer is theoretically able to use ~3 TB on 10 Mbit/s or up to ~300 TB on a 1000 Mbit/s line per month, although in practice the values will be significantly less. In a virtual private server, this will be shared bandwidth and a fair usage policy should be involved. Unlimited hosting is also commonly marketed but generally limited by acceptable usage policies and terms of service. Offers of unlimited disk space and bandwidth are always false due to cost, carrier capacities and technological boundaries.[3]
I can’t say it as a disadvantage of VPS hosting because many of our VPS hosting customers have server administrator to manage their VPS and they manage it in very efficiently manner. But this doesn’t everyone must have server administrator, we have content-rich knowledge base on VPS hosting for our self-managed customers.Also, a managed service option at very affordable price.