The I-35W/I-820 interchange on the North side of Fort Worth is about as impressive as interchanges can be, but all those square, boxy beams and uprights are pretty ugly looking.
I agree, many of the new freeways and interchanges built in DFW in the last 10 to 15 years have very unattractive concrete structures. This is especially true for the tolled managed lane facilities. The huge ramp structures at 635/35E and 820/121/183 are especially unsightly. The massive interchange at 35E and 121 is another interchange which could have been much nicer. Unfortunately unattractive structures are still being built, such as the ramps at SH 170 and IH 35W. These structures will probably be in service for a long term, perhaps until 2100.
Some recent work is very nicely designed, such as the Chisholm Trail parkway. The Dallas Mixmaster is okay, not attractive but not ugly.
For work in progress, the LBJ East project is using attractively designed structures. The piers at the 30/360 interchange are intermediate between attractive and ugly.
Houston does a much better job of using used architecturally enhanced designs. Everything built in the last 20 years is generally attractive. There are actually multiple themes used in different areas. The southeast side toward Galveston uses the "wave" design. Northwest Houston near the pine forests uses the pine-tree pier design. Central Houston mostly uses a nice enhanced pier design, I call it enhanced flare.