1) Disappointing 2) Unsatisfactory 3) Unsatisfying 
• (a.) Causing dissatisfaction; unable to give content; unsatisfactory; displeasing.
Dis·sat`is·fac'to·ry adjective Causing dissatisfaction; unable to give content; unsatisfactory; displeasing. « To have reduced the different qualifications in the different States to one uniform rule, would probably have been as dissatisfactory to some of the States, as difficult for the ...
causing dissatisfaction; unsatisfactory: dissatisfactory service.