Pretty much anything that gets used by many people ends up getting polished (the exception being the RNA-seq field, it's still pretty rough out there, but the research is still taking quite a while). And if you're writing software, your tool isn't going to get used until it's somewhat polished, or is so unique and essential in its purpose that people have to use it.
In terms of next-generation sequence analysis, Heng Li's BWA mapper and Samtools libraries are fairly good. His coding style is a bit terse for my tastes, but it keeps out people who don't know what they're doing, it's very clear code for semi-complicated algorithms, and BWA is some of the most reliable software I use everyday.
Regarding samtools, it doesn't sound very good from what I'm hearing:
"Look at the disgusting state of the samtools code base. Many more cycles are being used because people write garbage. For a tool that is intimately tied to research, the absence of associated code commentary and meaningful commit messages is very poor. The code itself is not well self documenting either."
As I said, the style is very terse, and I have my suspicions that this is by design to minimize the number of less-qualified programmers trying to submit sub-standard code back to the project. (Edit: since it's been 10 minutes and I still can't reply to tomalsky's comment, I should point out that my "suspicions" are a joke; read the linked code sample and judge its quality for yourself.)
I have dived deep into the samtools code, rewritten chunks of file I/O inside it, messed with alternate formats, and my personal experience is that it's been easier for me to change, adapt, and understand it then any other open-source C project I've tried to dive into, such as, say, GNU join.
If anybody can point to where samtools is using many more cycles than it has to, please let me know! The worst part about it is that the compression and decompression is not multithreaded, but that is being worked out, I believe.
samtools is among the better software in sequencing-data analysis. It is also great in defining formally the file format it uses. The same cannot be said of many other tools. For my recent work in RNA-Seq, samtools is the most robust and trustworthy tool I looked at and used, and I looked at almost every popular tool, the major exception being RSEM. If only all bioinformatics tools are more like samtools.
In terms of next-generation sequence analysis, Heng Li's BWA mapper and Samtools libraries are fairly good. His coding style is a bit terse for my tastes, but it keeps out people who don't know what they're doing, it's very clear code for semi-complicated algorithms, and BWA is some of the most reliable software I use everyday.
On the infrastructure side, Galaxy [https://main.g2.bx.psu.edu] is getting fairly good.
The BioConductor repository of R packages is extremely mixed. I don't like some of their architectural choices, but it's ended up working out OK.
I still use Michael Eisen's Cluster from a decade ago, along with Java TreeView.