。
But cleaning up the room is a pain.
Literal
However, room [obj-を] organize [nominalizer-のは] tiresome [and-し].
しかし 'however' opens the contrastive turn. 整頓する '(to) organize / tidy up' is a slightly formal alternative to 片付ける 'to clean up.' 面倒くさい '(a) pain / bothersome / tedious' is high-frequency everyday vocabulary for tasks one doesn't want to do — 面倒 'bother' + くさい (pejorative/intensifier suffix). ~のは nominalizes the clause as topic of evaluation. Trailing ~し hints at more reasons to follow.