You would not know these were refurbished, arrived in 2, days in perfect condition. They fit nicely in the ears, they don’t move once in place. Sound quality is excellent, they pair and connect right away ( the main reason I replaced my Cambridge Audio ones with these) and noise cancelling works a treat. The App works well too.
Overall very satisfied with both the Earbuds and the service from Sennheiser.

Bought recently & very impressed. Great sound, app & quality.
What you expect from a company like this

Posting a review of any product only days after purchase either reflects confirmation bias, or buyer's remorse.
It takes a while to fully form one's opinion. For earbuds, it takes trying different adapters, adjusting different custom app settings, and adjusting settings on ones phone. It's a process I've been through, and it is why I've taken a month to reflect on what I actually think of the Sennheiser CX Plus True Wireless, and post a review.
As preface before I get to this, let me emphasise that I own and have owned several Sennheiser headphones and earbuds in the past. My experience with these has overall been quite good, which is one of the reasons I opted for the CX Plus TW.

With respect to the physical aspect, the CX Plus comes with the recharging box that's slightly larger than ones from other brands. It's still pocketable, and holds a fair amount of energy for its purpose, so it's not necessarily negative.
However, the earbuds themselves are fairly bulky too. True, the batteries will last a good while (6+ hours!), but the size and shape make these rather uncomforable to wear for those, like me, with smaller ears. I find the CX Plus quite unpleasant to wear for a prolonged time, and have regularly been relieved to take these out of my ears. The CX Plus comes with a number of adapters, of which only the S (small) fits my ears.

The Sennheiser "smart control" app is decent, if fairly basic. I works quite smoothly, and allows some level of control over most settings. Of the more important settings, there's the option to chose codecs (the CX Plus supports most codecs, which is a big plus), and the option to switch devices (the CX Plus doesn't automatically switch, which can either be a plus or a negative).

While some reviewers rave about the superb quality of the CX Plus' sound (another reason why I opted for these), I'm underwhelmed. I find the sound quite tinny, with overstated middle and treble. This can be somewhat adjusted with the equalizer in the "smart control" app (and made extremely muddy with the useless "bass boost"), but never quite gets really to the level I expected given my experience with earlier Sennheiser products. Besides, decent earbuds shouldn't need an equalizer to "fix" their sound quality. I've never needed an equalizer with any of the other Sennheiser headphones I own(ed).

Lastly, as far as I'm concerned, the highly touted ANC is a total let-down. I find it barely cancels any noise at all, either actively or passively, and isn't worth the extra money. There are numerous inexpensive brands of earbuds that do a much better job at it.

Overall, the Sennheiser CX Plus True Wireless does not meet my expectations. Below is the list what I see as the negative and positive points.

Downsides:
- Poor fit for my ears
- Underwhelming, tinny sound
- Unimpressive ANC
- Relatively high price

On the upside:
+ Long battery life
+ Fairly decent app
+ Supports most popular codecs
+ May fit your ears better than mine

maybe my ears are too small, i cannot wear them prefectly, even i used small size. But others are really good, i did not feel it is refurbished.
I bought it also from my friend's recommendation.

Suprising true sound for the money. Excellent user interface (app required). The choice of ear-tips could be better.
Bottom line: highly recommended.