What are the disadvantages of LG nexus 5?

HI buddy
i m mukesh ,one of my friend having LG nexus 5 but he is facing problem with it and i have to know the disadvantages of this phone and i have to ask some question given below .
1. How is processor Speed?
2. is the phone having Heat problem?
3. Hanging problem ?
4. Battery back up?
5. Performance?
. Any other disadvantages and advantage. Most of the review are not positive pls advice me. Thanks.

I need to decide whether to buy or not, answer of above questions will be helpful for me..