IMHO, its been getting progressively better as time goes on. It has great support for React and Angular now, in addition to its own Blaze templating engine (I prefer Blaze, actually).
The data sync is fast enough to be useful for real-time games.
When it comes time to scale up, ditch the built-in mongo (or sql) and set up your DB cluster, and for the web bits, use something like https://github.com/meteorhacks/cluster and you are off to the horizontal scaling races.
In response to the linked posts criticism:
No API-based authentication: having a REST api to interface with Accounts is not there by default, but Meteor does support adding REST endpoints, where one could easily roll a solution that does a server-side auth and respond with an auth token which could be stored in the user's record as appropriate. I'd be surprised if there wasn't already a package available which does exactly this.
App shutdown: Once you are running a 'real' site, you will probably have a separate mongo instance. This solves most of the problems, however yes, it is still possible for some 'in-flight' data to be lost. Adding a maintenance mode like https://github.com/yogiben/meteor-maintenance-mode solves this though.
Subscriptions scalability: It's all about writing publish functions that only send what you need for a particular screen / template / page. In practice, it is not difficult and can scale up quite nicely: http://meteor.redandivory.com/
Server-side rendering for SEO: As the link points out, there are community packages that can make this happen. The beauty of meteor is the huge amount of community packages available that are almost universally of high quality. Their use should be encouraged, and is not considered "hacky".
My 2c.