half-and-half (as much one thing as the other) — ни то, ни се; так себе; серединка на половинку

Example: Last night's TV show was neither good nor bad; just half-and-half. — Вчерашняя программа была так себе, серединка на половинку

see also
[run of the mill]
[nothing to write home about]
[no great shakes]
[as common as dirt]
nothing to quicken your pulse