Yes...There are issues with them.
1. The Ego Cone threading is rather long, and the 510 well is deeper than some mods, so people have issues firing certain devices on them. I found that a lot of Evod's had trouble because the threads on the Ego collar on the Evod tend to bottom out before the post on the battery makes contact with the head. There are several work arounds to this. Mini PT 2's don't have this problem and most true 510 clearos don't. Also you can pull the bottom post on the head of your Evod a mm or so down and fix it. Some enterprising vapers have even pulled their heads a little bit and wrapped thread around it to prevent the Evod head post from getting pushed back up. Several of us have written to Innokin to fix this, and hopefully they will respond with either an adjustable middle pin, or a shallower connector.
2. The button press is a bit firm. This has been rectified to some extent, but it still does require a bit more effort. On the plus side, this tends to prevent accidental firing. on the minus side, you may have to adjust your grip. I use the side of my thumb to press the button and don't notice it anymore. Either my thumb got "pumped up" or the button has loosened. I don't know which, but I don't notice it.
3. You need to take care not to set your MVP on a table with standing liquid on it. The USB ports are exposed and on the bottom of the device. I make sure to set mine down on a dry surface or set it on it's side.
4. Being a new device, (less than a year old) there are no real life numbers yet on how long the unit will last. Based on typical LiIon charging rates, and the fact that the battery can last for at least 2 days between charges you SHOULD get at least 2 years out of it, but there are no real numbers out. There are many MVP1's which are alive and kicking. The biggest knock on those was the button which would fail prematurely. The new button on the MVP 2 may last longer.
5. Like any "non removable battery" device, the unit will eventually die. This is a deal breaker for a lot of people. But if you are looking at 45.00 a year. I take care of my gear and fully expect it to last longer than this.
The MVP overall is one "heck" of a package. It offers very high performance at a very reasonable price point. It's high capacity battery insures that most vapers can coax more than 2 days out of it before needing to charge, and the built in micro USB connector makes charging a breeze. It also allows you to vape while charging. It is a very solid unit that looks and feels like it will last quite some time.
Of course time will tell, but then again at $50.00 you're not taking a huge gamble.