7 days JR Pass price is almost same as round trip fare between Tokyo and Osaka by Shinkansen. That means if you have one way trip from Tokyo to Osaka or reverse, JR Pass is not worthwhile using. However if you add some trips when you stay in Osaka and Tokyo, you may use JR pass 7 days.
Train system in Kyoto may be complicated for you. There are three types of railway, JR, Kyoto City Subway and Private company’s railways. Actually it’s a key to travel in Kyoto smoothly and avoid wasting your valuable time. Of course city of Kyoto has city wide bus service. But during peak season, bus service runs behind the schedule sometimes due to traffic congestion.
And also, there are many types of deals, such as ICOCA, Kansai Thru Pass, JR Pass, Kansai Area Pass, Kyoto city pass. Each pass has different conditions. You have to understand which train system is covered by your pass.