Commercial software packages are generally a good option for complex engineering computations such as fluid dynamics and finite element analysis. Such software tends to be very costly to develop and therefore exists mainly for needs of wealthy industries such as automotive, aerospace, pharmaceuticals, etc.

Commercial software is generally only available for a limited number of platforms, usually Windows, Mac, and enterprise Linux distributions such as RHEL and SUSE. Furthermore, most commercial software is limited to specific versions of the supported operating systems. For example, some may not run on the latest version of Windows while others will only run on the latest version of Windows. This can be a nuisance for those who use multiple commercial applications, which may not be available for the same platforms.

Most commercial software also requires managing licenses that typically limit use to a single computer or require managing a license server, which most IT professionals agree is worse than a root canal. License servers must remain available nearly 24/7, so routine maintenance has to be scheduled at times when they would rather be sleeping or on vacation. License management requires a significant amount of expertise and effort, which should be considered as part of the total cost of ownership (TCO) of the software.

All that said, where there's a market for commercial software, the software often offers powerful capabilities not found elsewhere.

Many computer users fear open source software due to the lack of documentation and direct support from the vendor. These fears are largely unfounded, however. Support for commonly used open source software is usually provided by the user community in the form of online forums and email lists, which are open to everyone, and easily searchable. For all but the most esoteric issues, answers to most of your questions are usually already posted on the Internet and easily found with a simple web search.

It's true that nobody is obligated to help you with free software, but in reality, even in a community where many of the forum participants are rude and arrogant, there are almost always a few people ready and willing to help. Those who do it well will politely point you to existing answers to your question, so you can learn to find your own answers in the future. Even the crabby, rude responses are often helpful, though, and you will learn to be grateful and understanding once you get over the blow to your ego.

Contrary to common expectations, commercial software support does not guarantee answers to your questions either. Access to documentation is often restricted to registered customers who must log into a website to view or search it. Hence, a simple web search may not turn up any answers, because the search engines don't have access to the documentation or discussions. Phone support often involves automated menu systems, spending time on hold, and difficulty finding a support person who can answer the question. The process of finding answers to your questions about commercial software can often take a lot longer than for open source.

When determining whether to purchase a commercial software product, it's best to simply decide whether the features are worth the added purchase cost and effort associated with license management. It may be that the commercial software offers capabilities or performance that are not currently available in any open source equivalent. If this will greatly improve your productivity, then it may justify the costs.