ITER is a very cool project, and as someone that's contributed to parts of it, I can tell you with certainty that there is no meaning to the statement that it reached a "half way milestone". You'll note the article doesn't even mention what this milestone is. The reality is that work is ongoing but the timeline is always in flux, as some tasks turn out harder than expected while others (rarely) turn out easier than expected. Unlike building an office building or power plant, most of the work here is brand new and there are contributions from hundreds of private companies and universities each developing new pieces of technology that will be a part of ITER.
Further the article is misleading because it implies promise of a "new source of clean power by 2025". Even if there are no further delays (there have already been many) and first plasma is achieved in 2025, that would then only be the beginning of a minimum 5-10 year research campaign. ITER itself will not generate any electricity, it is only a research facility. If the 5-10 year research program starting in 2025 is extraordinarily successful, there may be just enough physics and engineering understanding to build a prototype power plant, which would likely take another 10-20 years to construct (ITER has been under construction for 10 years so far but design started in 1988 and first plasma is still 7+ years away). This prototype would then operate its own 5-10 year research program to demonstrate and optimize things. Only after that would there be any realistic hope of designing and building a commercially viable power plant (i.e. maybe in 2060). And that's if everything goes extraordinarily well, beyond the wildest dreams of anyone actually involved with technical aspects of fusion energy research.
That said, fusion energy is an important field of research and will possibly someday yield great benefits, and the science and engineering expertise gained as a result is well worth the cost, but these kinds of "hype" articles are not particularly representative of reality.