Is that the same Hale Irwin who does not like The Old Course?
I have never heard that Hale Irwin does not like The Old Course. Are you thinking of Scott Hoch?
I have played Irwin's Quail Creek, a muni in St. Louis and one of his early designs. There is nothing flashy about this course, but it is an above average muni. It is the right design for the intended use (low cost to construct and maintain, but still quality layout, challenging to all levels but not overly difficult so that pace of play will be good, able to with stand a lot of play, and able to tolerate the high variance of weather encountered in the Mid-West).
I know his company was involved in the restoration of Forest Park golf course in the city of St. Louis. I do not know the extent of Hale Irwin's involvement in the restoration, but the course is very much improved. The old layout had some character and some quirks, but also had quite a bit of flaws and needed a complete overhaul. The restoration was constrained due to other uses desired for some parts of the old course (the course is inside a city park with ponds, streams, woods, ballfields, tennis courts, museums, a zoo, ice rink, outdoor theater, walking/running/bike paths, and public roads). Yet the restoration resulted in a better course and layout, while preserving some of the best holes form the old course (in my opinion).
Boone Valley outside of St. Louis used to host a Senior Tour tournament, that was even adapted as a match play event for a couple of years. It also hosted last year's USGA Junior Championship. But I have never seen much of this course in person to be able to discuss its merits.
Per his web site his company was also involved in some restoration work at Old Warson C.C. (where he is a member and has been from most of his time in St. Louis) and at Norwood Hills C.C. I am not sure what this entailed.