Are there any obstructions in this theatre? Is the back of the stalls really far back? If you are sat at the sides, will you just see backs?
Personally I think it's a nice theatre. Good rake, decently comfortable seats, not too huge. Expect a drop in quality if you're taking cheaper seats (there are some at the sides where you ordinarily have to lean and still lose part of the stage, but those should be much better with a thrust configuration), but visibility should be fine in most of the auditorium.
Yes, small theatre. Even the back of the circle is fairly close to the stage. Only issues are that the back of the stalls has high seats with a foot rest, and leg room in the circle is restricted. My usual preference is the back row of circle seats with a gap next to them as there's a pillar in front of the "missing" seat (if you see what I mean!) as you can stretch your legs to the side and they are cheap. But changed layout for this show means these don't exist. So aisle seats on the back row probably best
But also since matinees are cheaper, top price matinee tix are £5 more than bottom price evening tix!