(Adjective) + 限(かぎ)りだ

限(かぎ)りだ is a structure that follows adjectives in order to indicate that something is 'extremely (A)', or 'as (A) as can be'. This grammar pattern is simply a mix of the noun 限(かぎ)り, 'limit', and the auxiliary verb だ, or です in the case of a polite sentence. Therefore, the literal meaning is just that something is 'the limit of (A)', where (A) is some describable feature.
限(かぎ)りだ will follow adjectives in their standard forms.

• こんな私(わたし)のためにこんな素晴(すば)らしい送別会(そうべつかい)を開(ひら)いてくれるなんて、嬉(うれ)しい限(かぎ)りです。
  I am very happy that you threw such an amazing farewell party for me.
• 宝(たから)くじで一等(いっとう)が当(あ)たったなんて、羨(うらや)ましい限(かぎ)りだ。
  Something like winning first place in a lottery is very enviable.
• 一分(いっぷん)遅(おく)れただけで不合格(ふごうがく)にされるなんて、残念(ざんねん)な限(かぎ)りだ。
  It's very disappointing that I failed just by being a minute late.
• 同僚(どうりょう)にあんなことを言(い)われて、不快(ふかい)な限(かぎ)りです。
  I'm very offended that my colleague said something like that to me.

限(かぎ)りだ is a fairly formal grammar point that simply aims to highlight the intensity of traits as perceived by the speaker. As this perception is something coming from the speaker, the adjective itself will often be an emotion that the speaker themselves is experiencing, rather than a direct quality of the object, such as its color or shape. Some examples of this are as follows.
嬉(うれ)しい - The feeling of happiness, as experienced by the speaker.
頼(たの)もしい - The feeling of reliability, as experienced by the speaker.
羨(うらや)ましい - The feeling of jealousy, as experienced by the speaker.
寂(さみ)しい - The feeling of lonliness, as experienced by the speaker.
恥(はず)ずかしい - The feeling of embarrassment, as experienced by the speaker.
心強(こころづよ)い - The feeling of reassurance, as experienced by the speaker.
As can be seen in all of the examples. The intensity of the adjective is something that will change depending on one speaker to the next, rather than something that the target is doing.