Kilka propozycji

serv•ice•a•ble (ˈsɜr və sə bəl)

adj.
1. being of service or help; useful.
2. wearing well; durable: serviceable cloth.
3. adequate; sufficient.
(...)
Adj. 1. serviceable - ready for service or able to give long service; "serviceable equipment"; "heavy serviceable fabrics"
functional - designed for or capable of a particular function or use; "a style of writing in which every word is functional"; "functional architecture"
practical - concerned with actual use or practice; "he is a very practical person"; "the idea had no practical application"; "a practical knowledge of Japanese"; "woodworking is a practical art"
useful, utile - being of use or service; "the girl felt motherly and useful"; "a useful job"; "a useful member of society"

http://www.thefreedictionary.com/serviceable

Definition of serviceable
1
: helpful, useful
2
: fit for use a serviceable design; also : of adequate quality
her serviceable but not exceptional voice — Irving Kolodin
(...)
Examples of serviceable in a sentence
I bought an old but still serviceable bicycle.
be sure to wear serviceable shoes if you're going to be walking on the rocks along the shore
Did You Know?
Someone who speaks serviceable Spanish isn't fluent in it but gets by pretty well. A serviceable jacket is practical and maybe even rugged. But serviceable sometimes damns with faint praise. A serviceable performance is all right but not inspired. Serviceable curtains aren't the ideal color or pattern, but they serve their purpose. A serviceable pair of shoes is sturdy but won't win you any fashion points.

https://www.merriam-webster.com/dictionary/serviceable