Update: Virtual Switches in vSphere Environment
Just FYI: a week after I wrote this (don't forget to go through the comments), VMware made it official:
…we’ve found that VMware’s native virtual switch implementation has become the de facto standard for greater than 99% of vSphere customers today. … Moving forward, VMware will have a single virtual switch strategy that focuses on two sets of native virtual switch offerings – VMware vSphere® Standard Switch and vSphere Distributed Switch™ for VMware vSphere, and the Open virtual switch (OVS).
Kidding aside, makes (business) sense from VMware's perspective, I guess.
Talking from my perspective, I always stress that it's wise to evaluate how much you're going to regret vendor lock-in versus vendor agnostic (once more went over that during a presentation I gave today). Not saying of course one shouldn't buy products & services like ACI & NSX, plenty valid use cases, but as engineers and architects I feel we have to obligation to look critically in what is offered and if it addresses the actual customer needs (problems ?).