There is nothing wrong with a simple battery charger like that. Primarily they protect the battery from over voltage but just realize that they leave a whole lot of energy on the table. With a sophisticated charger you can use a smaller PV array to keep a larger battery fully charged and across deeper discharges. In a word it'll be more efficient.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
"They say the test of literary power is whether a man can write an inscription. I say, 'Can he name a kitten?'" -- Samuel Butler