NetSuite is an extremely powerful and inclusive package of applications that are extremely well-integrated.
For SMBs who've outgrown Quickbooks or other "smaller" accounting packages, it's a major improvement.
For manufacturing concerns looking to gain more traction and control over their processes, it is far beyond what lower-priced ERP systems provide. Again, it us a major improvement.
NetSuite is extremely extensible through external interfaces, 3rd party add-ons, internal scripting and through customizations.
Implemented correctly, it is relatively fast, and with its browser-based interface, there are no client issues and never any need for IT to upgrade a client version on every workstation because a new feature-set has been implemented.
It's CRM is adequate, useful, and given NetSuite's signature internal integration, it is easy to implement an effective lead-to-cash system.
The ecosystem also has multiple vendors who sell integration services, for example, there are a number of SalesForce to Netsuite integration partners who can (relatively) quickly connect the two systems. On the backside, the same is true of many popular shipping, warehouse management and other packages. Or, you can roll your own JSON connectivity.
NetSuite is not easily deployed, and requires expertise to get things mostly right the first time. They address this in their ecosystem by encouraging customers to work with NetSuite partners -- VAR firms that have undergone certifications -- to deploy the system.
There is a steep learning curve, even for system analysts familiar with other ERP, CRM and web commerce platforms.
There is a saying in the NetSuite community that is very true: "you can do anything with NetSuite, but it is going to cost you." Those costs may be development hours for internal developers, fees paid to partners, license costs for addons and integrations, etc. etc. Count on it with any major NS effort.
NetSuite is usually quite reliable, but it can and will "get slow" from time to time, and there are infrequent outages that can last a few minutes to an hour or more. These never come at a good time (is there ever a good time?) and getting information regarding status of repairs can be frustrating.
Free advice: vett your NetSuite partner carefully, and make sure that they can and will provide effective ongoing support. Some firms are better than others at this, and it is a good question to ask references before you hire anyone.
Plan on your implementation taking longer than you expect. This is true with most ERP implementations, NetSuite included.
Support from the company itself can be an exercise in frustration, but persistence and insistence can really help.