[3] Writers in the 19th century commented on the "lofty square tower",[4] the "very good" east window,[5] and the "many elegant monuments";[6] the clergyman and antiquarian Harry Longueville Jones called St Mary's "one of the best specimens of an old parish church in the island".

[7] In the 21st century, one writer has noted the "impressive lychgate"[8] and a guide to the buildings of the region calls it "the most important church in north west Anglesey".

[10] In the middle of the 19th century the porch entrance was blocked off and replaced by a window, and since then access to the church has been through a door on the west side of the tower.

[9] Further work was undertaken in 1860, and some repairs were carried out in the chancel and south chapel in the 1930s under the architect and historian Harold Hughes.

[1] James Williams, rector of St Mary's from 1821 to 1872, helped to establish the Anglesey Association for the Preservation of Lives from Shipwreck in 1828, in the wake of a storm that caused a boat to sink with 140 deaths.

[13] Angharad Llwyd, writing when Williams was at St Mary's, noted that "this benevolent gentleman, aided by his lady, ever alert in the cause of humanity, are generally among the first on the shore, in case of accident, well supplied with restoratives, and other necessaries, to comfort and protect the suffering mariners.

[15] St Mary's is a medieval church, built using rubble masonry dressed with freestone and displaying Perpendicular details.

[3] A survey of the church in 1937 by the Royal Commission on Ancient and Historical Monuments in Wales and Monmouthshire noted the window's "crude workmanship and design.

[3] The tower has external buttresses and the door on the west side is set in a pointed arch frame with a hood mould.

[3][8] Behind the parapet at the top of the tower, there is a short spire in the shape of a pyramid, made from wood and covered in slates.

[10] The 14th-century doorway from the nave into the vestry has a pointed head in a square frame, and was described in the 1937 survey as having an "unusual design".

[2] It was given this status on 12 May 1970, as "a fine rural parish church, incorporating significant early Medieval fabric, including a 12th-century chancel arch".

[3] Cadw (the Welsh Government body responsible for the built heritage of Wales and the inclusion of Welsh buildings on the statutory lists) also notes the "good late Medieval additions, including a fine 16th-century arcaded chapel", and says that St Mary's is of "special interest" because of its early date, "and for the quality of its later detail".

[3] Writing in 1833, before the restoration of 1847, Angharad Llwyd described the church as "a spacious ancient structure, partly in the Norman style, with a lofty square tower, of rude architecture".

[4] She noted the "massive circular pillars and arches" in the chancel, and the "peculiar good taste" of the architecture of the recently rebuilt rectory.

[6] Writing in 1862, the clergyman and antiquarian Harry Longueville Jones said that it was "one of the largest churches in this division of Anglesey"[7] He said that it had recently been "judiciously repaired and restored" by James Williams and was "now one of the best specimens of an old parish church in the island", adding that the east window was "good in detail and in execution".

"[5] He described the churchyard as "secluded, and shaded by fine trees" and the tower as "rude and plain", noting that the "open bell arch" on the west side was comparable to the one at St Mary's Church, Llanerchymedd.

[8] A 2009 guide to the buildings of the former county of Gwynedd calls St Mary's "the most important church of north-west Anglesey" and says that it has "an unusual plan".