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 Pickup - Imelda / '08 Tacoma TRD - Donna
'09 Kawasaki KLR650
'98 Rhygin Juke SS / '12 Gunnar Rockhound 29 / '16 REEB Dikyelous
"Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty. Nobody is able to achieve this completely, but the striving for such achievement is in itself a part of the liberation and a foundation for inner security. " --Albert Einstein