Recs.
Updated
Specs
Pros
Pro Great performance for the price
The Snapdragon 801 paired with 3GB of RAM is the same hardware we saw in high end phones from 2014. Instead of going with modern budget processors, OnePlus went with the best performing processor from 2014 to provide good performance while keeping prices low. This works, and scores about 47 000+ on AnTuTu v6 and 2350 in Geekbench.
When it launched, its GPU would only perform at about 30% of its potential. This was a bug, which has been fixed. Gaming performance now is good - much better than most other budget phones.
Pro Good build quality with good materials
Unlike most budget phones, the OnePlus X was designed and built to look and feel good. The rear panel is made of glass, and helps the phone feel much more expensive than it really is. The phone feels sturdy, and the quality is higher than you'd typically expect from a budget phone.
Pro Quick and easy notification managing
The OnePlus X features a notification slider on the left of the phone. It toggles between Android's 3 notification modes - Ring, vibrate, and silent. You can use it while the phone is still in your pocket, meaning you don't need to pull your phone out to silence it (or to check if it's on silent) - great for students, work meetings, and frequent movie-goers.
Cons
Con Poor battery life
The 2525mAh battery provides enough power to go a full day for light users, but most will need to recharge their phone before the day is done. Playing a 90 minute video dropped battery by 27%, and GSMArena only rates the battery at 54h in their tests - a lackluster result.
Con No fast charge or NFC
Not every user will use these features, but for those who do these are pretty big omissions. Fast charge is helpful especially for phones such as this which will often require recharging before the end of the day. NFC would have been able to take advantage of Android Pay, as well are wireless printing (if you have compatible hardware) or utilizing NFC tags for automating some tasks.
Con Incomplete US carrier compatibility
The OnePlus X lacks LTE band 17, which is the primary band for AT&T. In many areas, the best you will get on AT&T and related MVNOs is HSPA+ rather than LTE. It also lacks band 12 for T-mobile, which is rolling out to many markets now and will improve indoor coverage. Additionally, it is incompatible with both Sprint and Verizon, although this is the norm for GSM unlocked phones.