How to configure GRE Tunnel on Cisco IOS Router

Rene
I saw an example where the tunnel interfaces were used in the IP ROUTE command. Is there a disadvantage using the tunnel interfaces. The example is below. Thanks

CLI Command Examples

R1(config)# int tunnel 0
R1(config-if)# ip address 192.168.2.1 255.255.255.0
R1(config-if)# tunnel source g0/1
R1(config-if)# tunnel destination 201.150.200.6
R1(config-if)# tunnel mode gre ip
R1(config-if)# exit
R1(config)# ip route 192.168.3.0 255.255.255.0 192.168.2.2

R3(config)# int tunnel 0
R3(config-if)# ip address 192.168.2.2 255.255.255.0
R3(config-if)# tunnel source g0/1
R3(config-if)# tunnel destination 201.150.200.1
R3(config-if)# tunnel mode gre ip
R3(config-if)# exit
R3(config)# ip route 192.168.1.0 255.255.255.0 192.168.2.1