Whether or not you should pursue VMware certifications depends on your job role and which certificates you're interested in.
Certification is usually a requirement to obtain partner status with a vendor, which is often the biggest driver for systems integrators to hold multiple certifications. Individual staff members use certification to prove their mastery of a technology when they're seeking advancement, whether that's within an organization or with a new employer. Some people simply like to be measured and reassured of their abilities.
VMware offers certifications from Associate to Expert level in Data Center Virtualization, Cloud, End-User Computing and Network Virtualization. These certifications suit a range of job roles and skill sets.
If a certification tests a job role that you already perform, you should be able to pass the exam without a lot of studying. If you plan to use the certification to break into a new position, you will need to acquire additional skills before taking the exam. There are formal training courses, and many people spend their own time studying to advance their careers.
VCA, VCP, VCAP and VCDX
VMware's Certified Associate-level certifications (VCAs) have a fairly low barrier to entry. They are ideal for a staff member who wants to show willingness to learn or demonstrate an awareness of a new area. There is free online training for VCAs. You should plan to dedicate about half a day to watch the training videos, plus a little more reading time.
VMware's Professional-level (VCP) certifications are suited to technical staff who use the product the certification exam covers some of the time, but have a lot of other responsibilities. For example, the VCP-DT, which is in the End-User Computing certification track, proves the holder has a level of knowledge in implementing and operating a simple Horizon View environment.
VMware requires that you attend its week-long training course before you can achieve your first VCP qualification. Once you hold one VCP, there is no mandatory training for further certifications. The VCP exam is administered by Pearson VUE.
If you spend most of your time working with VMware's products, you may want to proceed from VCP to the Certified Advanced Professional level (VCAP). VCP certifications are a prerequisite for VCAPs. They demonstrate a much deeper knowledge about designing and operating VMware-based environments. The exams are much longer, and some use live lab exercises rather than a question-and-answer format. The exams are also difficult, so it's important to be well prepared.
The VMware Certified Design Expert (VCDX) is VMware's most arduous certification and is not suited to every job role. The certification tests design and troubleshooting skills. The final test is an oral exam, plus a whiteboard presentation in front of a panel. Most candidates take months to prepare for the final defense, and they must have already completed the VCP and two VCAP exams. At the time of writing there are fewer than 200 people in the world with VCDX qualifications.