Should I buy a house w/ 4 apartments, private sale?

My grandma is offering to sell me and my dad her 2 story house which has an apartment in the basement, 1st floor, 2nd floor, and attic. We would both co-own the house paying $5,000 down each and I would own the upper half of the house to collect its rent. After $10,000 down we would owe $70,000 on the house total and it is in fantastic condition with a lot of work done on it. We would split property tax, insurance, and "mortgage".

Estimated monthly cash flow for my share of the house:

+ $300/mo for attic (Already rented, 5+ years)
+ $550/mo for 2nd floor (Already rented, 5+ years)
- $250/mo for mortgage
- $50/mo for insurance ($600/yr)
- $50/mo for property tax ($600/yr)
= $500 per month positive flow

Current tenants already pay their own utilities and future tenants will as well.
The bank says the house was appraised at $120,000 before all the work was done to it over the past 7 years. My question is would this be a solid investment if the inspection comes out positive? I'm not very experienced when it comes to real estate and haven't bought property before. So what do you think?

Extra info:
The attic tenant is sort of the "handyman". He shovels/plows the snow during the winter and mows the grass along with fixing basic plumbing/electrical issues we've had in the past.

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