This place is always full of life.
'Pieno' = PIE-no. 'Vita' = VI-ta.
Use this to comment on the atmosphere and energy of the gathering. It is a positive observation that opens discussion about the venue, the host, and the social circle. It works as both a genuine compliment and a conversation starter.
'Pieno di vita' (full of life) is a warm Italian expression. 'Essere pieno di' (to be full of) + noun is very versatile: pieno di energia (full of energy), pieno di gente (full of people). 'Sempre' (always) implies this is a recurring quality.
C'è un'energia bellissima stasera.
There is a wonderful energy tonight.
Energy as an abstract quality of the gathering
Mi piace l'atmosfera informale.
I like the informal atmosphere.
Commenting on the relaxed, casual character of the party
La gente qui è sempre molto simpatica.
The people here are always very likeable.
Complimenting the social quality of the group
Italian social gatherings often reflect the Italian concept of 'vivacità' — liveliness, animation, expressiveness. A good Italian party is loud, warm, and full of simultaneous conversations. Quiet, reserved gatherings are sometimes described as 'un po' freddine' (a bit cold) — the ultimate Italian social criticism.