Basically, the show was really The Hugh Jackman Show with Hugh really playing a character named Peter Allen. The show wasn't performed like a regular 'book' show -- he spoke to the audience the entire time. Even in the middle of a 'scene' he would make comments to the audiences, etc. Also, Hugh made each performance different since he ad-libbed and played with the audiences nightly. At every performance he would stop the show when latecomers arrived and address them as to why they were late, etc. The 2nd Act Opener was the Reno Sweeney Night Club scene which he would interrupt in the middle to address the audience, this time to single-out a female (or male) audience member. The moment was always the same but the interaction was always different. At one performance I attended this literally stopped the show for about 15 minutes. At another performance, Elvis Costello was in the audience and Hugh brought him up and had him perform 2 songs with the onstage band as Hugh sang back-up with the 3 onstage backup singers (from the Reno Sweeney Night Club scene). This stopped the show for almost 30 minutes. This sorta stuff is what made the show AND Hugh such a enormous 'theatrical event' that season. I saw the show 3 times and EVERY performance was an event due to all this ad-libbing.
As for the cast recording goes -- it's just a recording of the numbers, so the visual and the 'live' moment are missing UNLESS you saw the show 'live'. All the songs are Peter Allen songs, so they are not character driven in any way UNLESS you saw the show and saw in what context they were done. Most are 'performance' songs so they needed to be seen 'live'.
Also kudos needs to be said about the supporting cast, most notably Isabel Keating's chillingly channeling of Judy Garland. She captured Judy's essence which left you with your mouth open everytime she came on stage. Even her stage exits (that walk) were pure Judy Garland.
The critics hated the show but word-of-mouth is what drove ticket sales: you HAVE to see Hugh Jackman in this show. People kept going back and back to see it simply because of Hugh's 'live' schtick -- it WAS something to experience since EVERY night was almost a totally different show. You never saw the same show twice. Barbara Cook was also a frequent visitor to the show, plus it was likely that you would see a 'celebrity' at the performance you attended, which was also kinda nice.
Now...was the show/play any good? WHO CARES?! Just attending a performance was the thing. It was the backbone to how the evening progressed so we just followed along. We were there to have a great time with Hugh and he gave you more than you ever wanted. AND he never missed a performance!
Whew! That was a mouthful.