VISUAL ARTS: ALL IN ALL, this year's 178th Annual Exhibition of the Royal Hibernian Academy is one for the history books.

The show opened unusually late because, cutting it close in the face of general economic collapse, the academy managed to effect a much-needed and successful transformation of its headquarters in Ely Place. True, it still needs to raise significant funds to realise the potential of the redevelopment, which is not going to be easy, but if it hadn't managed to get the builders in at the tail-end of the boom, it might have been waiting another 10 years.

Then, everything that's been done - with architects HJ Lyons - comes across as being really sensible, from enhancing the main Gallagher Gallery to the design of the "circulation system", the staircases and other aspects of interior access, not to mention the provision of studios on the roof.

The Gallagher Gallery is now formidable indeed, to the extent of being daunting. It could cope with all manner of large-scale art - just the kind of exhibitions that, perhaps, will become harder and harder to stage in terms of finance and logistics. But there's no point in being anything other than ambitious. While the Annual Exhibition runs until December 13th, it seems fair to say that, reflecting the economic malaise, sales have been sluggish for what is usually one of the most commercially successful shows in the calendar, apart from being one of the most popular, which it certainly still is.

So visitors can expect the dual pleasure of checking out the show and sniffing around the overhauled building with its cafe and bookshop. The 178th Exhibition also sets the seal on a slow, generational process that's been going on for the last decade or more: the ceding of artistic vision to an incoming administration. Each year the visible signs of the erstwhile academy, once dominant and uninspiring, have become sparser. This change is not simply generational, though.

There has been a conscious broadening of the academic agenda, and one of the prime movers in the process of transformation (of the building, the organisation and the artist base), the late Conor Fallon, is commemorated in the exhibition. Fallon, who sadly died in October last year, devoted several years and a huge amount of energy - surely at the expense of his own work - to the academy, and deserves huge credit for his efforts (as detailed by RHA director Patrick Murphy in the exhibition catalogue).

What of the exhibition itself? In many respects, it too is a tribute to Fallon and his successors in the organisation. This is not because it's so big that the hanging is, necessarily, desperately unflattering to a lot of the work - that's in the nature of the annual shows, and is indicative of a creditable openness and accessibility, even though those artists whose work was rejected will not feel that way, often with reason. Despite the broadness of its selection committee, the academy is not exactly fair and certainly not infallible, but there is an approximate justice to its procedures, which bears favourable comparison with any open-submission show.

Anyway, you might not feel too flattered at being given the thumbs up if, as in the case of Patrick Michael Fitzgerald, your painting (an outstanding one) ends up in a virtually impossible slot, one that renders it close to invisible. But that is the name of the academic game. In a way, those assigned to the vast Gallagher Gallery are in as difficult a position. The walls are big, but there's simply no chance of a breathing space between the paintings, and it's well-nigh impossible to see anything in the relative isolation that many pieces call for.

In this tough environment, Michael O'Dea fares well, although mind you, he has the run of what has often been described as the best wall in the gallery. Even so, the gutsy determination of each of his works, across several genres, is very convincing. David Crone's paintings also stop you in your tracks, not because they are boldly assertive, as are many fine pieces in the show, but because they draw you into their intricate, ambiguous spaces. There is a comparable subtlety to the paintings of Diana Copperwhite and Barrie Cooke, and the same is true, though in quite a different way, of Veronica Bolay's landscapes, usually of open spaces that have a hushed, expectant quality.

Landscape, an academic staple, is strong in the show, and it's good to encounter works that you can't take in at a glance, that aren't predictable. These include Jacqueline Stanley's view of the Grand Canyon, Gary Coyle's drawing, At Sea, and Stephen Loughman's spare, stylised Picnic. Loughman's works draw on unspecified film settings, showing us scenes that we know but don't know how we know. Perhaps the eucalyptus trees in Picnicindicate that the location is Hanging Rock.

There's an almost mythical simplicity to Barbara Warren's idyllic Figure Resting Near the Sea, while Martin Gale is on excellent form, particularly with his atmospherically exact The Mist Rolls In, which could well symbolise Ireland at this historical moment.

Figures, another staple, whether in group compositions or portrait form, also feature prominently. Nell McCafferty, startlingly and assertively nude in Daniel Mark Duffy's snapshot-like study, has attracted headlines. Carey Clarke has been busy with a meticulous series of portraits, including a fine painting of his daughter. For interesting takes on figure or figures, look to Colin Harrison, Una Sealy, Gene Lambert, Stephen Forbes and Sahoko Blake.

Janet Mullarney's grid of carved heads, Earthly Creatures, stands out among the sculpture, which is memorably displayed on marshalled plinths. Sarturio Alonso's head of Lorna Cope Corrigan, a three-dimensional photographic composite, is a show-stopper.

Over the last few years, photography has gradually established a substantial presence and now looks comfortably at home in the show. Appropriately, given the compendious nature of the RHA, the selection ranges from traditional pictorial approaches to the medium, via anecdotal snapshots to more contemporary idioms. Outstanding among the latter are Mary McIntyre's mist-shrouded view of a wooded lakeside, Veil XVI, which prompts us to rethink the way we look at a landscape, and strong portrait images by Simon Burch and Jackie Nickerson. But all this only scratches the surface of an exhibition that runs to 530-plus works, most of them worth seeing.

• The 178th RHA Annual Exhibition is at the Royal Hibernian Academy, Gallagher Gallery, 15 Ely Place, Dublin, until Dec 13