"The HTML5 client oozed out over years, only achieving feature parity more than two years after initial release."
To be fair, they are supporting 6.0, 6.5, 6.7 and 7.0 which is a huge burden. See https://lifecycle.vmware.com/#/
They did the initial client in fat form on client a la HyperV but without the MMC bollocks. That worked well and was fast *sigh*. Then we got a sodding huge lump of Flash stuff. Quite fast once it wheezed into life (5-20 mins from start), quite buggy, very odd in its initial incarnations. Got better and was very stable in its last incarnations. The HTML5 jobbie grew up rather ginger but has improved and despite being rather drab still, is now pretty decent. The local host webby interface is nearly good enough nowadays and stable but all of VMware's webby things are still a bit odd in places. Not BES (shudder) odd or Cisco firewall odd or HPE Procurve odd or Fritzbox odd but still quite ... odd.